Contributor

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16 Messages

Wednesday, April 1st, 2026 4:20 PM

Frequent Latency spikes / and loss of internet / looking for next steps

Been Dealing with issue for well over a year.

Frequent internet drops, high latency.

Rebooting modem, entire network often does not fix issue and modem may not connect for hours(like it did several times yesterday.

It rarely affects my two next door neighbors.

everything may seem fine, all data from modem (channels, power, etc seem ok) and then all of a sudden massive uncorrectables and internet will be down and reboot doesn't help.

Fall of 20024:

Xfinity replaced the RG11 from Coax tap at top of pole with rg6. and then replaced old direct burial RG11 with new RG11 in conduit to the house (about 180-200 feet total length. Now RG6 to RG11 and then the rg 6 inside the house)

They replaced the PPC POE / MOCA filter at the house, and then single 2 way Commscope splitter.

At that time I changed from older netgear CM1000v2 modem to arris SB8200. and same issues

Then I had all new rg6 installed from the xfinity commscope 2 way splitter on the side of the house. One direct line to the TV box and one direct line to the modem.

same issues

Modem changed from Netgear CM1000v2 to Arris sb8200

Same issues.

Changed to CM3000 modem yesterday and same issue

I have unifi UDM SE for router and networking

Here is image showing issue over the last week.

Yellow line showing massive latency spikes

Red line showing packet loss spikes

Purple line showing upload

Line below showing "green" when internet ok and red when internet was out. Last night, i would reset modem, barely get it up and running to see netgear stats with massive uncorrectables and it would shut down.

Took many hours for it to come back on line last night.

This morning internet working and saw this on modem:

then I was able to reboot the network

and get

It is making it very difficult to work from home.

It isn't a specific time of day.

Looking for help with further diagnostics or how to document issues.

I don't know if this is problem at the node in area, the tap / feed to the pole from the street.

Should the line from the Coax tap, down pole and to the house all be RG11?

The few techs that have been here, changing the lines on outside....all works when they are here.

Thanks for any advice

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Contributor

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16 Messages

12 days ago

Happened again, interrupting work at 2:15pm, in and out for several minutes

spikes in packet loss and/or latency

Internet drops and now modem with massive uncorrectables despite full reset of entire network.

(I don't see way to add photos to a comment on my post)

Contributor

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16 Messages

11 days ago

Happened again multiple times today. Starting around 10:45am, down for several hours. Neighbor two doors down had no issues with his internet. only mine

Multilpe reboots of modem and unable to get signal, finally had to leave unplugged and use backup so i could work.

After modem finally connected in the afternoon, I decided to replace the POE MOCA filter on outside of house with brand new Belden PPC one. POEGB-1G70CW (same one used by xfinity)

Internet remained fine, until 9:35pm tonight with massive packet loss and internet loss. multiple reboots of modem, over 30 minutes to get a signal.  Had difficulty locking upstream channels. Occasionally I could log in to modem and would show very high 55+ power levels on upload channels.

After 30 minutes, modem finally able to stabilize and start working.

Contributor

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16 Messages

10 days ago

Tech coming sunday.

this is the modem log overnight. lots of T3 time outs. Internet out, several times for over an hour or more

Any insight into things to make sure the Tech checks?

Things I can document further now or during the visit?

Fri Apr 03 06:17:37 2026 (Notice (6)) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 06:16:33 2026 (Notice (6)) DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 06:16:32 2026 (Notice (6)) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 06:16:27 2026 (Notice (6)) TLV-11 - unrecognized OID;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Notice (6)) Honoring MDD; IP provisioning mode = IPv6
Time Not Established (Critical (3)) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 05:20:00 2026 (Critical (3)) 16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 05:20:00 2026 (Critical (3)) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 05:20:00 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 04:52:29 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 04:44:40 2026 (Critical (3)) DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 04:43:53 2026 (Critical (3)) DHCP failed - DHCP Request sent, No DHCP REPLY received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 04:40:05 2026 (Critical (3)) TFTP Request Retries exceeded, CM unable to register
Fri Apr 03 04:40:05 2026 (Critical (3)) TFTP failed - Request sent - No Response;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Critical (3)) DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Critical (3)) DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Critical (3)) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 04:22:21 2026 (Critical (3)) No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 04:19:00 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:31:54 2026 (Critical (3)) No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:26:56 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:20:51 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:12:52 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:08:08 2026 (Critical (3)) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:08:08 2026 (Critical (3)) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:08:08 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:55 2026 (Critical (3)) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:55 2026 (Critical (3)) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:55 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:49 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:42 2026 (Critical (3)) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:42 2026 (Critical (3)) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:42 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:29 2026 (Critical (3)) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:29 2026 (Critical (3)) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:29 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:20 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:16 2026 (Critical (3)) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:16 2026 (Critical (3)) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Fri Apr 03 00:07:16 2026 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

(edited)

Contributor

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16 Messages

10 days ago

This person sure sounds like having the same issue, but much better at describing the situation

https://forums.xfinity.com/conversations/your-home-network/intermittent-upstream-impairment-repeated-16event-t3-timeout-clusters-with-postevent-degradation-requesting-plant-escalation/69c1e42934f516488eef0c9f

Official Employee

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3.2K Messages

10 days ago

@user_0lud8l 

 

Hi there, thank you for taking the time to lay all of this out. Seriously, this is one of the most detailed write-ups we’ve seen, and it helps a lot.

 

Based on everything you’ve already done, swapping modems multiple times, replacing interior and exterior lines, and still seeing latency spikes, packet loss, and those bursts of uncorrectables, this is very unlikely to be anything inside your home at this point. You’ve already ruled that out in a big way.

 

What you’re describing lines up much more with an intermittent signal issue upstream. That could be something at the tap, the line feeding the pole, or even further back toward the node. The fact that everything looks fine while a tech is on site and then degrades later is a big clue. Intermittent noise or signal ingress can be hard to catch unless it’s actively happening during testing.

 

To your question about cabling, RG11 is typically used for longer runs like from the tap to the home, while RG6 is standard for shorter runs and inside wiring. What you have now sounds correct, so there’s nothing there that immediately raises a red flag.

 

The key detail in your post is the pattern. Everything looks normal, then suddenly you get a spike in uncorrectables, latency jumps, packet loss hits, and the modem can’t recover even after a reboot. That points to a signal quality issue hitting the line, not a hardware or configuration issue.

 

We know how disruptive this is, especially working from home, and you’ve already done more troubleshooting than most. Let’s take it the rest of the way. 

 

Can you initiate a direct message and start with your full name and address? To start a direct message, you must be signed in. Please click the "Direct Messaging" icon in the top right of the page next to the bell, and send your message to "Xfinity Support". Talk to you there!

Contributor

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16 Messages

@XfinityAirelle​ 

I am logged in, and in direct messaging, the "compose" button is greyed out and i get red circle / slash icon and can not create a direct message.

My concern with the cabling, and unlikely to be the issue, is that it is not all RG11 for nearly 200 foot run to the side of my house. there is RG6 comes from the coax tap, right near the transformer on a pole that supplies power to three houses.

My concern about the pattern:

1. it is sporadic

2. it can last minutes to 4-5 hours, like it did overnight

3 It does not affect my neighbor, right next door. His service comes from a different coax tap. 

Gold Problem Solver

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27.3K Messages

10 days ago

... i get red circle / slash icon and can not create a direct message. ...

In your Forum user Profile Settings is "Opt Out from Direct Messaging" checked? If it is, clear it, click Save, and try again.

Contributor

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16 Messages

I appreciate the help

Contributor

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16 Messages

9 days ago

Tech is coming tomorrow, but trying to keep things documented as may help others.

Most of the day yesterday was fine. I woke up at 8am and internet had been down for many hours.

It took 5 reboots of the modem to get back up, so i could finally see the modem logs:

Downstream power seems ok, levels ok. upstream ofdma seems on low side, but can finally see the constant t3 timeouts for hours on the log.

And I am also looking closer and trying to see where my tap comes from. I'm seeing that the  coax tap line to the pole on my property may have been damaged when power company used long boom saw on a large truck to trim a tree. They had to go between cable and phone lines. (we do not have regular phone service, so have no idea if those are damaged). Best photos i can get with just a cellphone

(i was not there when it happened, but it is my best guess). 

The coax tap line is now not secured to the guide wire from the pole at the street to the pole on my property very well, and seems to be getting loose.  The wire(s), that wrap around the guide wire and the coax tap, have been cut/snapped/damaged and now the coax line is coming away from the guide wire.

Current Time: Sat Apr 04 08:05:40 2026

Startup Procedure
Acquire Downstream Channel: 573000000 Hz  Locked
Connectivity State:          OK       Operational
Boot State:                  OK       Operational
Security:                   Enabled   BPI+
IP Provisioning Mode:       Honor MDD   IPv6 only


Downstream Bonded Channels
Channel LockedStatus Modulation ChannelID  Frequency     Power    SNR   Correctables Uncorrectables     
      1     Locked     QAM256     36     573000000 Hz     -1.2     43.2     0     0
      2     Locked     QAM256     13     435000000 Hz     -0.9     43.8     0     0
      3     Locked     QAM256     14     441000000 Hz     -1     43.7     0     0
      4     Locked     QAM256     15     447000000 Hz     -0.8     43.7     0     0
      5     Locked     QAM256     16     453000000 Hz     -0.8     43.8     0     0
      6     Locked     QAM256     17     459000000 Hz     -0.9     43.7     0     0
      7     Locked     QAM256     18     465000000 Hz     -1.2     43.5     0     0
      8     Locked     QAM256     19     471000000 Hz     -1.2     43.5     0     0
      9     Locked     QAM256     20     477000000 Hz     -1.4     43.3     0     0
     10     Locked     QAM256     21     483000000 Hz     -1.5     43.2     0     0
     11     Locked     QAM256     22     489000000 Hz     -1.4     43.3     0     0
     12     Locked     QAM256     23     495000000 Hz     -1.3     43.4     0     0
     13     Locked     QAM256     24     501000000 Hz     -1.2     43.4     0     0
     14     Locked     QAM256     25     507000000 Hz     -1.2     43.4     0     0
     15     Locked     QAM256     26     513000000 Hz     -1     43.5     0     0
     16     Locked     QAM256     27     519000000 Hz     -1.2     43.4     0     0
     17     Locked     QAM256     28     525000000 Hz     -1.5     43.3     0     0
     18     Locked     QAM256     29     531000000 Hz     -1.7     43.1     0     0
     19     Locked     QAM256     30     537000000 Hz     -1.9     42.9     0     0
     20     Locked     QAM256     31     543000000 Hz     -2.3     42.7     0     0
     21     Locked     QAM256     32     549000000 Hz     -2.2     42.7     0     0
     22     Locked     QAM256     33     555000000 Hz     -2.1     42.8     0     0
     23     Locked     QAM256     34     561000000 Hz     -1.9     42.9     0     0
     24     Locked     QAM256     35     567000000 Hz     -1.5     43.1     0     0
     25     Locked     QAM256     37     579000000 Hz     -1.2     43.2     0     0
     26     Locked     QAM256     38     585000000 Hz     -1.2     43.2     0     0
     27     Locked     QAM256     39     591000000 Hz     -1.4     43.1     0     0
     28     Locked     QAM256     40     597000000 Hz     -1.7     42.9     0     0
     29     Locked     QAM256     41     603000000 Hz     -2     42.8     0     0
     30     Locked     QAM256     42     609000000 Hz     -2.2     42.7     0     0
     31     Locked     QAM256     43     615000000 Hz     -2.3     42.7     0     0
     32     Locked     QAM256     44     621000000 Hz     -2.1     42.5     0     0

Upstream Bonded Channels
Channel   LockedStatus  ChannelType ChannelID   SymbolRate        Frequency       Power     
      1       Locked       ATDMA     20       5120 Ksym/sec       35600000 Hz       44.0 dBmV
      2       Locked       ATDMA     18       5120 Ksym/sec       22800000 Hz       43.3 dBmV
      3       Locked       ATDMA     19       5120 Ksym/sec       29200000 Hz       43.5 dBmV
      4       Locked       ATDMA     17       5120 Ksym/sec       16400000 Hz       43.0 dBmV
      5       Not Locked       Unknown      0       0       0       0.0
      6       Not Locked       Unknown      0       0       0       0.0
      7       Not Locked       Unknown      0       0       0       0.0
      8       Not Locked       Unknown      0       0       0       0.0

Downstream OFDM Channels
Channel   LockedStatus  ProfileID  ChannelID    Frequency       Power       SNR/MER    ActiveSubcarrier    Unerror    Correctable   Uncorrectable
      1     Locked     0 ,1 ,2 ,3     193     690000000 Hz     -1.72 dBmV     42.2 dB     208 ~ 3887     7279699     2998570     95
      2     Locked     0 ,1 ,2 ,3     194     957000000 Hz     -2.62 dBmV     41.0 dB     148 ~ 3947     7216696     5205973     0

Upstream OFDMA Channels
Channel   LockedStatus    ProfileID    ChannelID    Frequency       Power
      1     Locked     12 ,13     43     36200000 Hz     36.8 dBmV
      2     Not Locked     0      0     0 Hz     0 dBmV

Event Log
         Time               Priority     Description
Sat Apr 04 07:49:41 2026     Notice (6)     CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 07:48:57 2026     Notice (6)     DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 07:48:56 2026     Notice (6)     DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 07:48:51 2026     Notice (6)     TLV-11 - unrecognized OID;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Time Not Established     Notice (6)     Honoring MDD; IP provisioning mode = IPv6
Time Not Established     Critical (3)     SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 06:15:05 2026     Critical (3)     16 consecutive T3 timeouts while trying to range on upstream channel 8;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 06:15:05 2026     Critical (3)     Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 06:15:05 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:13:17 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:04:21 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:03:28 2026     Critical (3)     No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:03:21 2026     Critical (3)     DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:02:37 2026     Critical (3)     No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:01:43 2026     Critical (3)     DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:01:31 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:01:01 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:00:53 2026     Critical (3)     No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:00:43 2026     Critical (3)     DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:00:42 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 03:00:00 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:59:56 2026     Critical (3)     No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:59:48 2026     Critical (3)     DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:59:07 2026     Critical (3)     No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:58:59 2026     Critical (3)     DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:58:57 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:58:19 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:57:57 2026     Critical (3)     No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:57:48 2026     Critical (3)     DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:57:47 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:57:04 2026     Critical (3)     DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:58 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:17 2026     Critical (3)     No Ranging Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:03 2026     Critical (3)     16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:03 2026     Critical (3)     Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:03 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:01 2026     Critical (3)     16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:01 2026     Critical (3)     Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:56:01 2026     Critical (3)     Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
Sat Apr 04 02:54:53 2026     Critical (3)     Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

(edited)

Contributor

 • 

16 Messages

9 days ago

Logged into my neighbors modem, but it is a rented XB7.

Can anyone confirm, if the event logs are blocked?  I couldn't find them to compare to my own issues and drops and T3 issues

I can see:

It has an "Uptime" of several days, and mine has dropped multiple, multiple times today alone

I can see that his downstream channels have billions of unerrored codewords, which is fine.

I can also see that for his entire uptime, it is showing "Zero" for correctable codewords and "Zero" for uncorrectable codewords.

I currently, since modem last able to get signal, have thousands and thousands of each

Official Employee

 • 

270 Messages

Thank you so much for keeping us all updated here user_0lud8l! Much appreciated.

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

Contributor

 • 

16 Messages

8 days ago

Tech came to house. They were very nice and listened to the situation. Modem had been down for hours.

Tech checking levels at house and modem. Can't find specific issue. Did recommend changing out a grounding / pass through block inside to Belden PPC ones, so i did

They were able to see that my neighbor, two doors down, on a different coax tap has been up for many / many days and generally zero "correctable" and "uncorrectable" errors

The tech will generate report, needs to include supervisor / maintence for further guidance given the issue.

Current status with modem up for less than 50 minutes:

Modem able to obtain signal

All down stream channels starting to develop uncorrectable errors.

Downstream OFDM with many millions of correctable codes, and up to ~1300 uncorrectable code words

Official Employee

 • 

3.3K Messages

Hello @user_0lud8l sounds like the tech is going to open a maintenance request to have the line checked. How long has it been since the tech visited your home I would like to check your account to see if that request has been submitted. Please return to direct messaging when you can to assist further. 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

Contributor

 • 

16 Messages

7 days ago

Several drops overnight again up to 20 plus minutes. 

Lots of "Critical (3)     16 consecutive T3 timeouts while trying to range on upstream channel"

So took modem / router outside and connected directly to end of the RG11 from pole, bypassing all home wiring.

Distance from Coax tap to house about 180-200 feet of RG6 on pole and then RG11 underground. So modem and router connected about 180-200 feet from the tap

two drops / loss of internet in two hours. same / similar intermittent packet loss and internet drops

i can list all logs if needed, but trying to keep concise.

Initially:

Downstream power with levels greater than 10. SNR 43

Upstream powers: 38

Downstream OFDM: very quickly >300,000 correctable down stream errors and a hundred uncorrectable errors

Upstream OFDMA: power 30.5

within an hour internet dropped, T3 time out, packet loss

Next modem log:

Downstream power now 8-9.  SNR 43. 400s-1100s of  uncorrectable errors across the channels

Upstream: power 41.3

Downstream OFDM: power 10.58 and 13.48 now millions of correctable errors and >1300 uncorrectable errors

Upstream OFDMA: power 33.8

within next hour internet dropped again, several T3 time outs, various other warnings.

Next Modem Log:

Downstream power: 8.6-9.8. SNR 43 now correctable continue to increase from 1000 to over 4000.

Upstream power: 41.5

Downstream OFDM: power 10.68 and 13.68 SNR 43.6. now >12,000,000 correctable and nearly 6000 uncorrectable errors

Upstream OFDMA: power 33.8

Is this a fair Test of situation?

Is this more likely to be the supply lines or Coax tap / aerial issue?

Could this still be issue inside my house 

Official Employee

 • 

1K Messages

We appreciate the information user_0lud8l 👍 If you're still having timeout and connection issues, we want to make sure you're followed up with on where things left off with our technician. Before departing, did they let you know if they'd be getting back in touch with you?

 

Contributor

 • 

16 Messages

The tech said he was writing up his report and including supervisor and maintenance. He mentioned that it could take a week, and I understand that.  I “think” he said they would call. I’m just still trying things here, to see if any issue here on my side of things. 

(edited)

Official Employee

 • 

1K Messages

Well it's good to know they are getting that report in, and I'm confident they'll continue to work on things 👍 We can follow up with you after a few days to see if any additional contact has been made, and if not we can certainly continue to work on things from there. Please follow up with us in our direct message conversation if you have any additional questions.

Contributor

 • 

16 Messages

1 day ago

still happening. haven't heard back from tech visit last week.

no rain. no wind. just all of a sudden, will loose connection, huge T3 timeouts / upstream difficulty.

will take multiple modem reboots. sometimes/often disconnecting/reconnecting the line at pole coming directly from service tap or sometimes at side of house before modem able to connect

I have same issues when putting modem on the end of the RG11 run from the pole, and avoiding the home wiring altogether.

My next door neighbors have no such issues.

Waiting on next steps from tech / maintenance.

Contributor

 • 

16 Messages

1 day ago

Update:

Another tech visit scheduled for tomorrow

Contributor

 • 

16 Messages

3 hours ago

Tech today was very thorough.

He checked the line at the service tap, at the top of the power pole and hopefully this is the issue.  This was installed over a year ago

This was the connector at the service tap, at the top of the pole.  It was way too long, at 1/2", and severely damaged / cut / sharp edges at the end. It may have damaged that service tap port and been source of intermittent losses. He redid the connector and used a different port on the service tap.

Will continue to monitor.

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