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fjcle1
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Tuesday, April 1st, 2025 8:13 PM

Troubleshooting internet stability and packet loss issues

Looking for the magic solution! I have been battling with packet loss and internet stability issues for more than a year now. Many attempts to resolve through Xfinity customer support calls have left me defeated. I've dealt with it, but it's incredibly frustrating.

I'm experiencing intermittent, but frequent packet loss and latency spikes across all devices on my home network regardless of WiFi or Ethernet connection. This problem presents as:

  • Slow load times, buffering, and/or a grainy image while streaming TV/movies and while scrolling through instagram/facebook.
  • Delayed hits, rubber banding, and on screen notifications about "high latency" or "packet loss" while gaming.

I've made the following efforts to resolve the issue:

  • Obvious things like power cycling and factory resets on both modem and router.
  • New Cat 5e and RG6 cables, new couplers.
  • Ensured a direct RG6 line from street to modem (no splitters).
  • In November 2023 I bought a Netgear CM1100 modem
  • Xfinity tech ran new Coax lines from the telephone pole to my exterior wall and from the exterior wall through my crawl space to my interior coax jack.
  • In December 2025 I bought a Netgear RS280 router.
  • Updated Modem, Router, and NIC adapter firmware to the latest available.
  • Started monitoring with PingPlotter 5 and observing Modem/Router event logs.

My current setup is a CM1100 Modem connected to a RS280 Router using the LAN aggregation configuration. I'll include event logs, cable connection stats, and PingPlotter results in subsequent replies.

Would greatly appreciate any help or suggestions!

Question

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Updated 

17 days ago

 • Edited

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fjcle1

New Poster

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7 Messages

2 months ago

NetGear CM1100 Modem Cable Connection Stats

Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency
<tabindex=-1>Startup Procedure</tabindex=-1>
Procedure Status Comment
Acquire Downstream Channel 477000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enable BPI+
IP Provisioning Mode Honor MDD IPv6 only
<tabindex=-1>Downstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power SNR / MER Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked QAM256 20 477000000 Hz 10.1 dBmV 43.9 dB 113340379 0 0
2 Locked QAM256 13 435000000 Hz 10.4 dBmV 44.3 dB 112435004 0 0
3 Locked QAM256 14 441000000 Hz 10.4 dBmV 44.2 dB 112449370 0 0
4 Locked QAM256 15 447000000 Hz 10.4 dBmV 44.2 dB 112452866 0 0
5 Locked QAM256 16 453000000 Hz 10.7 dBmV 44.4 dB 112456339 0 0
6 Locked QAM256 17 459000000 Hz 10.6 dBmV 44.2 dB 112459951 0 0
7 Locked QAM256 18 465000000 Hz 10.2 dBmV 44.1 dB 112463545 0 0
8 Locked QAM256 19 471000000 Hz 10.3 dBmV 44.1 dB 112468115 0 0
9 Locked QAM256 21 483000000 Hz 10.3 dBmV 44.1 dB 112471562 0 0
10 Locked QAM256 22 489000000 Hz 10.2 dBmV 44.1 dB 112475981 0 0
11 Locked QAM256 23 495000000 Hz 10.1 dBmV 43.8 dB 112479547 0 0
12 Locked QAM256 24 501000000 Hz 10.0 dBmV 43.9 dB 112483133 0 0
13 Locked QAM256 25 507000000 Hz 9.9 dBmV 43.6 dB 112486864 0 0
14 Locked QAM256 26 513000000 Hz 9.8 dBmV 43.6 dB 112490962 0 0
15 Locked QAM256 27 519000000 Hz 9.4 dBmV 43.4 dB 112494658 0 0
16 Locked QAM256 28 525000000 Hz 9.3 dBmV 43.4 dB 112498113 0 0
17 Locked QAM256 29 531000000 Hz 9.3 dBmV 43.3 dB 112502139 0 0
18 Locked QAM256 30 537000000 Hz 9.3 dBmV 43.2 dB 112505519 0 0
19 Locked QAM256 31 543000000 Hz 9.1 dBmV 43.2 dB 112509401 0 0
20 Locked QAM256 32 549000000 Hz 8.8 dBmV 43.1 dB 112513141 0 0
21 Locked QAM256 33 555000000 Hz 8.8 dBmV 43.1 dB 112516419 0 0
22 Locked QAM256 34 561000000 Hz 8.6 dBmV 42.9 dB 112520477 0 0
23 Locked QAM256 35 567000000 Hz 8.6 dBmV 42.9 dB 112524376 0 0
24 Locked QAM256 36 573000000 Hz 8.6 dBmV 43.0 dB 112511318 0 0
25 Locked QAM256 37 579000000 Hz 8.3 dBmV 42.7 dB 112531509 0 0
26 Locked QAM256 38 585000000 Hz 8.1 dBmV 42.6 dB 112535577 0 0
27 Locked QAM256 39 591000000 Hz 8.0 dBmV 42.6 dB 112539026 0 0
28 Locked QAM256 40 597000000 Hz 8.0 dBmV 42.4 dB 112542716 0 0
29 Locked QAM256 41 603000000 Hz 7.8 dBmV 42.4 dB 112546579 0 0
30 Locked QAM256 42 609000000 Hz 7.2 dBmV 41.9 dB 112550454 0 0
31 Locked QAM256 43 615000000 Hz 7.1 dBmV 41.9 dB 112545776 0 0
32 Locked QAM256 44 621000000 Hz 7.1 dBmV 41.8 dB 112547320 0 0
<tabindex=-1>Upstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power
1 Locked ATDMA 1 16400000 Hz 42.0 dBmV
2 Locked ATDMA 2 22800000 Hz 42.0 dBmV
3 Locked ATDMA 3 29200000 Hz 42.0 dBmV
4 Locked ATDMA 4 35600000 Hz 42.0 dBmV
5 Not Locked Unknown 0 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Hz 0.0 dBmV
<tabindex=-1>Downstream OFDM Channels</tabindex=-1>
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier Number Range Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked 0, 1, 2, 3 193 690000000 Hz 7.2 dBmV 39.0 dB 208 ~ 3887 8882456 8666849 0
2 Locked 0, 1, 2, 3 194 957000000 Hz -1.1 dBmV 30.0 dB 148 ~ 3947 8885618 8026029 0
<tabindex=-1>Upstream OFDMA Channels</tabindex=-1>
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked Unknown 0 0 Hz 0 dBmV
2 Not Locked Unknown 0 0 Hz 0 dBmV
Current System Time: Tue Apr 01 14:03:55 2025
System Up Time: 0:42:13

NetGear CM1100 Modem Event Log

** I cleared the log and rebooted the modem today. 3 critical events on reboot, don't know what they mean **

Time Priority Description
2025-04-01, 19:22:38 Critical (3) UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
2025-04-01, 19:22:38 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;
2025-04-01, 19:22:37 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;
2025-04-01, 19:22:22 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2025-04-01, 19:22:17 Critical (3) UCD invalid or channel unusable;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;

(edited)

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XfinityChelseaB

Official Employee

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1.7K Messages

2 months ago

Hello @fjcle1, Thanks so much for taking a moment out of your day to leave a post on our community forum and we would be happy to help. 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.

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0

EG

Expert

 • 

110.5K Messages

2 months ago

@fjcle1 @XfinityChelseaB 

Please circle back here and post any possible solutions for the issue here in these open public forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.

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fjcle1

New Poster

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7 Messages

As an update, i'm still having the same issues. Had a busy April so have not gotten back to this. I purchased a Netgear CM3000 cable modem yesterday to try something different. It has a diagnostic feature built in that is notifying me of "Poor downstream power levels" and points to voltages being out of spec (too high).

Cable Diagnostic

Status: Poor

Action:
[Downstream Power Level]
Try these actions (Click the Refresh button after each step):
1) Make sure the coaxial cable is tightly connected.
2) Remove any unnecessary splitters.
3) Replace any required splitters.
4) Contact your service provider for troubleshooting help.

CM Status: Good

Downstream Status: Poor

    Downstream Power Level: Poor
    Downstream power is poor (11.6dBmV). The recommended level is between -10dBmV to 10dBmV.

    Downstream SNR Level: Good

Upstream Status: Good

    Upstream Power Level: Good


Current Time: Wed May 07 08:54:50 2025

Startup Procedure
Acquire Downstream Channel: 621000000 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     44     621000000 Hz     7.8     42.3     0     0
      2     Locked     QAM256     13     435000000 Hz     11.6     44.8     0     0
      3     Locked     QAM256     14     441000000 Hz     11.5     44.8     0     0
      4     Locked     QAM256     15     447000000 Hz     11.5     44.8     0     0
      5     Locked     QAM256     16     453000000 Hz     11.6     44.8     0     0
      6     Locked     QAM256     17     459000000 Hz     11.3     44.6     0     0
      7     Locked     QAM256     18     465000000 Hz     10.7     44.4     0     0
      8     Locked     QAM256     19     471000000 Hz     10.9     44.4     0     0
      9     Locked     QAM256     20     477000000 Hz     10.7     44.3     0     0
     10     Locked     QAM256     21     483000000 Hz     10.8     44.3     0     0
     11     Locked     QAM256     22     489000000 Hz     10.5     44.1     0     0
     12     Locked     QAM256     23     495000000 Hz     10     43.9     0     0
     13     Locked     QAM256     24     501000000 Hz     9.3     43.6     0     0
     14     Locked     QAM256     25     507000000 Hz     9.5     43.6     0     0
     15     Locked     QAM256     26     513000000 Hz     9.7     43.8     0     0
     16     Locked     QAM256     27     519000000 Hz     9.2     43.5     0     0
     17     Locked     QAM256     28     525000000 Hz     9.2     43.5     0     0
     18     Locked     QAM256     29     531000000 Hz     9.3     43.5     0     0
     19     Locked     QAM256     30     537000000 Hz     9.3     43.5     0     0
     20     Locked     QAM256     31     543000000 Hz     9.3     43.5     0     0
     21     Locked     QAM256     32     549000000 Hz     8.9     43.2     0     0
     22     Locked     QAM256     33     555000000 Hz     9.1     43.3     0     0
     23     Locked     QAM256     34     561000000 Hz     8.8     43.1     0     0
     24     Locked     QAM256     35     567000000 Hz     8.9     43.2     0     0
     25     Locked     QAM256     36     573000000 Hz     9     43.2     0     0
     26     Locked     QAM256     37     579000000 Hz     8.7     43.1     0     0
     27     Locked     QAM256     38     585000000 Hz     8.4     42.9     0     0
     28     Locked     QAM256     39     591000000 Hz     8.5     42.9     0     0
     29     Locked     QAM256     40     597000000 Hz     8.4     42.9     0     0
     30     Locked     QAM256     41     603000000 Hz     8.2     42.8     0     0
     31     Locked     QAM256     42     609000000 Hz     7.7     42.5     0     0
     32     Locked     QAM256     43     615000000 Hz     7.7     42.5     0     0

Upstream Bonded Channels
Channel   LockedStatus  ChannelType ChannelID   SymbolRate        Frequency       Power     
      1       Locked       ATDMA      3       5120 Ksym/sec       29200000 Hz       35.8 dBmV
      2       Locked       ATDMA      2       5120 Ksym/sec       22800000 Hz       35.8 dBmV
      3       Locked       ATDMA      1       5120 Ksym/sec       16400000 Hz       36.0 dBmV
      4       Locked       ATDMA      4       5120 Ksym/sec       35600000 Hz       36.0 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     8.28 dBmV     41.9 dB     208 ~ 3887     209919156     184120932     0
      2     Locked     0 ,1 ,2 ,3     194     957000000 Hz     0.48 dBmV     37.8 dB     148 ~ 3947     211903373     182680363     456

Upstream OFDMA Channels
Channel   LockedStatus    ProfileID    ChannelID    Frequency       Power
      1     Locked     12 ,13     41     36200000 Hz     30.0 dBmV
      2     Not Locked     0      0     0 Hz     0 dBmV

(edited)

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17 days ago

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fjcle1

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Event Log
         Time               Priority     Description
Wed May 07 09:53:33 2025     Notice (6)     CM-STATUS message sent. Event Type Code: 16; Chan ID: 194; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Wed May 07 09:53:12 2025     Notice (6)     DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Wed May 07 09:53:11 2025     Notice (6)     DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Wed May 07 09:53:06 2025     Notice (6)     TLV-11 - unrecognized OID;CM-MAC=;CMTS-MAC=;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=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Wed May 07 09:51:53 2025     Critical (3)     Resetting the cable modem due to docsDevResetNow
Time Not Established     Critical (3)     SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Tue May 06 19:18:18 2025     Critical (3)     Resetting the cable modem due to docsDevResetNow
Time Not Established     Critical (3)     SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Tue May 06 17:22:35 2025     Critical (3)     Resetting the cable modem due to docsDevResetNow
Time Not Established     Critical (3)     SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=;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=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Time Not Established     Critical (3)     Resetting the cable modem due to docsDevResetNow

(edited)

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