Skip to main content

    Support

    Offers

S
skylighter
1st Topic
1st Like

Visitor

 • 

3 Messages

Tuesday, May 27th, 2025 12:22 AM

Frequent Loss of Internet

Over the last few days I've started to encounter frequent loss of internet connection to my modem / router. These events last 1-5 minutes and happen probably about once an hour or two. I've tried to reset the modem / router, I've factory reset it, I've disconnected and reconnected the coax cable which has no visible issue. I have a Netgear C7000v2 that has worked well with my 1gig plan for 4 years now without any issues. I've attached the logs and data from the router. I don't think it's the modem / router going bad but not sure. Any troubleshooting through the Xfinity assistant recognizes the problem as fixed by the time I hit the 10 minutes given for a router restart, even if I don't restart the route. Any tips / solutions or is this something that needs a tech to come take a look at?

1970-1-1, 00:02:27 Notice (6) Honoring MDD; IP provisioning mode = IPv6
1970-1-1, 00:02:19 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:02:14 Warning (5) ToD request sent - No Response received;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:02:11 Critical (3) TFTP Request Retries exceeded, CM unable to register
1970-1-1, 00:02:11 Critical (3) TFTP failed - Request sent - No Response;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:08 Warning (5) ToD request sent - No Response received;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:52 Notice (6) Honoring MDD; IP provisioning mode = IPv6
1970-1-1, 00:00:43 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:40 Notice (6) WiFi Interface [wl1] set to Channel 153 (Side-Band Channel:N/A) - Reason:INIT
1970-1-1, 00:00:40 Notice (6) WiFi Interface [wl0] set to Channel 11 (Side-Band Channel:N/A) - Reason:INIT
1970-1-1, 00:00:37 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
2025-5-26, 18:05:57 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 18:03:46 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 18:02:02 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 18:02:02 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:58:32 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:57:50 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:56:16 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:56:14 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:55:06 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:54:59 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:54:55 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:54:11 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 15:54:11 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
2025-5-26, 14:54:14 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.1;CM-VER=3.0;
1970-1-1, 00:00:44 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:37 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
2025-5-26, 13:30:31 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
2025-5-26, 13:30:24 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
2025-5-26, 13:30:22 Critical (3) No UCDs Received - Timeout;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
2025-5-26, 13:30:05 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:35 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:30 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:28 Critical (3) No UCDs Received - Timeout;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:10 Critical (3) No UCDs Received - Timeout;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:53 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:43 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:41 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:38 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=******************;CMTS-MAC=******************;CM-QOS=1.0;CM-VER=3.0;
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 519000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 21 519000000 Hz -2.5 dBmV 39.9 dB 4 0
2 Locked QAM256 22 525000000 Hz -2.3 dBmV 39.8 dB 7 0
3 Locked QAM256 23 531000000 Hz -2.4 dBmV 39.8 dB 7 0
4 Locked QAM256 24 537000000 Hz -2.5 dBmV 39.9 dB 7 0
5 Locked QAM256 25 543000000 Hz -2.3 dBmV 40.1 dB 5 0
6 Locked QAM256 26 549000000 Hz -2.4 dBmV 40.1 dB 4 0
7 Locked QAM256 27 555000000 Hz -2.5 dBmV 40.1 dB 5 0
8 Locked QAM256 28 561000000 Hz -2.2 dBmV 39.7 dB 7 0
9 Locked QAM256 29 567000000 Hz -2.3 dBmV 40.3 dB 2 0
10 Locked QAM256 30 573000000 Hz -2.1 dBmV 40.3 dB 2 0
11 Locked QAM256 31 579000000 Hz -2.2 dBmV 40.2 dB 6 0
12 Locked QAM256 32 585000000 Hz -2.1 dBmV 40.1 dB 5 0
13 Locked QAM256 34 591000000 Hz -1.9 dBmV 40.1 dB 3 0
14 Locked QAM256 35 597000000 Hz -2.3 dBmV 40 dB 8 0
15 Locked QAM256 36 603000000 Hz -1.9 dBmV 40.1 dB 2 0
16 Locked QAM256 37 609000000 Hz -2.3 dBmV 40.1 dB 7 0
17 Locked QAM256 38 615000000 Hz -2.9 dBmV 40.4 dB 0 0
18 Locked QAM256 39 621000000 Hz -3.3 dBmV 40.3 dB 0 0
19 Locked QAM256 40 627000000 Hz -3 dBmV 40.3 dB 2 0
20 Locked QAM256 41 633000000 Hz -3.1 dBmV 40.8 dB 0 0
21 Locked QAM256 42 639000000 Hz -3.4 dBmV 40.4 dB 0 0
22 Locked QAM256 43 645000000 Hz -3.1 dBmV 40.8 dB 0 0
23 Locked QAM256 44 651000000 Hz -3.6 dBmV 39.9 dB 0 0
24 Locked QAM256 45 657000000 Hz -3.1 dBmV 40.3 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 2 5120 Ksym/sec 16300000 Hz 54 dBmV
2 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 54 dBmV
3 Locked ATDMA 4 5120 Ksym/sec 29200000 Hz 53.8 dBmV
4 Locked ATDMA 5 5120 Ksym/sec 35600000 Hz 53.8 dBmV
5 Locked ATDMA 6 2560 Ksym/sec 40400000 Hz 53.3 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

Question

 • 

Updated 

4 days ago

 • Edited

37

2

0

Accepted Solution

EG

Expert

 • 

110.7K Messages

7 days ago

The upstream power too high /out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, animal chews.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.


Good luck with it !

4

skylighter

Visitor

 • 

3 Messages

Thank you for the response! I am in an apartment complex so there's only a foot or two of coax cable between me and where I lose insight into any splitters or fittings. I've replaced with the old coax cable with a brand new one and still have the same upstream power per the router page, but will see if this resolves the issue. If not I'll reach out for a tech visit.

Like

Reply

7 days ago

0

XfinityJohnG

Official Employee

 • 

1.8K Messages

@skylighter You can let us know here if that replacement cable did not resolve the connection issue, and we can proceed from there. 

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

Like

Reply

6 days ago

0

skylighter

Visitor

 • 

3 Messages

While it did not change the upstream power changing the coax cable seems to have fixed the drops. I didn't see any signs of corrosion on the outside, but the cable due to where the modem is in relation to the outlet was bent, and I guess damaged internally.

Like

Reply

4 days ago

XfinityAmandaB

Official Employee

 • 

2.2K Messages

 

skylighter that can happen, kinks, pinches, punctures, can impact the wires running inside the line. If the upstream signals are still impacting your connection, we would be happy to help take a closer look with you.  If you could send our team a direct message with your full name, the name listed on the account (if different), and the service address associated with your account, I'd be more than happy to look into this for you. To send a Direct Message, please click on the chat icon in the top-right corner of the screen, next to the bell icon, and then type or select "Xfinity Support" to initiate a direct message.

 

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

Like

Reply

4 days ago

0

EG

Expert

 • 

110.7K Messages

7 days ago

My pleasure ! Please let us know how things go.

0

0

forum icon

New to the Community?

Start Here