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cheeseplus
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09/16/2026 11:59 PM

Arris S34 + 2GB plan having to reset modem daily

  1. I've went through the useless Xfinity assistant multiple times to no avail
  2. A technician did come out and add a splitter + attenuator to lower the signal as it was too strong for the S34
  3. Prior to the technician visit, as well as after still getting daily errors and warnings of the following variety
    1. T3/T4 timeouts
    2. RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value
    3. MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
    4. US profile assignment changes
  4. Problematically it seems large, high bandwidth downloads like Steam seem to cause service to fall over
    1. which if the modem is barely holding onto the signal it pushes over the edge
    2. as a game developer this is something I do daily and am regularly losing connection
  5. Most days we have to reboot the modem when we wake up and some days several times a day
  6. Our prior modem + plan (S33 + 1GB) had almost no issues

What I'd really love for is to have a senior tech come out and determine if there is a line issue from the drop (before the house) and if not explore alternate options such as getting a new firmware/bootfile provisioned. It's bad enough that using the connection fully causes issues but having to reset the modem several times daily makes me regret upgrading at all as it's causing nothing but issues. All the automated tests say the signal and modem are "fine" but that's clearly not the case so I'm posting here as a last resort before exploring more drastic options.

Happy to provide modem logs or anything else but not keen on repeating the basics troubleshooting over and over - the rest of the networking gear is professional grade so I'm confident this is either a modem or more likely line issue.

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24 minutes ago

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XfinityChelseaB

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2.6K Messages

26 days ago

Hello @cheeseplus, 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. I will need to pull up your account to investigate this further. 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. Click "Sign In" (If necessary). Click the "Direct Messaging" Icon. Click the "Start New Conversation" (pencil and paper) icon. In the “To:” line, type "Xfinity Support". As you type, a drop-down list will appear. Select "Xfinity Support" from that list. An "Xfinity Support" graphic will replace the "To:" line. Type your message in the text area near the bottom of the window. Press Enter to send it. How to: Direct Message Within The Forum.

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cheeseplus

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7 Messages

24 days ago

Since this post we've not experienced any dropout overnight but it still does seem like I can reliably push the connection to failure with Steam (anything above 90MB/s seems to do it).

Still getting a fair amount of T3 timeouts:

09/20/2026 10:34:57	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/20/2026 09:58:17	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/20/2026 08:47:04	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/20/2026 05:57:03	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/20/2026 02:32:29	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/20/2026 01:55:50	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 21:54:36	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 18:53:18	Notice	US profile assignment change. US Chan ID: 41; Previous Profile: 11; New Profile: 12.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 18:47:03	Notice	US profile assignment change. US Chan ID: 41; Previous Profile: 12; New Profile: 11.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 18:29:59	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 18:12:29	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 18:03:02	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 17:59:22	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 13:52:08	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 10:26:59	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 09:50:54	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 05:49:41	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 03:01:02	Notice	US profile assignment change. US Chan ID: 41; Previous Profile: 10; New Profile: 12.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 02:51:02	Notice	US profile assignment change. US Chan ID: 41; Previous Profile: 12; New Profile: 10.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 02:25:05	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/19/2026 01:48:28	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 21:47:14	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 18:22:40	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 17:45:59	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 14:28:08	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 14:09:55	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 14:09:43	Notice	DS profile config update. DS Chan ID: 194.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 14:09:12	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 14:09:10	Notice	DS profile config update. DS Chan ID: 194.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 13:44:47	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 12:32:28	Notice	US profile config update. US Chan ID: 41.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 12:32:18	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 11:50:13	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 10:20:13	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 09:50:47	Notice	US profile assignment change. US Chan ID: 41; Previous Profile: 11; New Profile: 12.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 09:45:02	Notice	US profile assignment change. US Chan ID: 41; Previous Profile: 12; New Profile: 11.;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 09:43:33	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 05:42:18	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 04:16:36	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 02:17:45	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/18/2026 01:41:05	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

09/17/2026 21:39:51	Critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:ac:39;CMTS-MAC=**:**:**:**:06:00;CM-QOS=1.1;CM-VER=3.1;

[Edited: MAC Obfuscated for Prviacy Concerns]

(edited)

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cheeseplus

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7 Messages

2026-10-14 update:

  • 3rd tech came out on Oct 3rd and testing device found no issues with ping or throughput (but never really mentioned power)
  • suggested that it might be the Arris S34 modem
  • swapped to Netgear CM3000
  • same issues
    • any multi-threaded download seems to cause the connection to lock up the modem requiring restart
    • most noticeable with Steam or Perforce (revision control) syncs
      • bandwidth capping, either at the router level or application level doesn't help - even a 40MB/s cap encounters same issue
      • these are work tools so I can't avoid them
    • crashes the internet every morning

Given the high, out-of-spec power levels the modems are reporting I did try adding a 6db forward path attenuator which clearly does help bring the power levels down but ultimately has done nothing to prevent connection loss.

Current status: I've reach out to the tech from last visit as they wanted me to report back if the modem swap didn't help 

Attaching some logs to illustrate what the new modem is reporting - largely identical errors to the S34

Wed Oct 14 09:56:35 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 10 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Wed Oct 14 09:56:01 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;Wed Oct 14 09:56:00 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;Wed Oct 14 09:55:55 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 = IPv6Time 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 Oct 09 12:44:59 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 Oct 09 07:31:14 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 12 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Fri Oct 09 07:23:29 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Fri Oct 09 06:21:14 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 12 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Fri Oct 09 06:12:16 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Thu Oct 08 21:11:13 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 12 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Thu Oct 08 21:03:43 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Thu Oct 08 16:26:13 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 12 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Thu Oct 08 16:17:08 2026 (Warning (5))  Dynamic Range Window violationThu Oct 08 16:17:08 2026 (Warning (5))  RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Thu Oct 08 16:15:43 2026 (Notice (6))  US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Thu Oct 08 12:46:21 2026 (Warning (5))  Dynamic Range Window violationThu Oct 08 12:46:21 2026 (Warning (5))  RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=[Edited: “Personal Information”];CMTS-MAC=[Edited: “Personal Information”];CM-QOS=1.1;CM-VER=3.1;Thu Oct 08 12:45:33 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;Thu Oct 08 12:07:53 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;Thu Oct 08 12:07:52 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;Thu Oct 08 12:07:46 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 = IPv6Time 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;Wed Oct 07 15:32:47 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;Wed Oct 07 12:43:12 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;Tue Oct 06 12:42:59 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;Tue Oct 06 10:13:58 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;Tue Oct 06 10:13:08 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;Mon Oct 05 16:12:39 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;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 Oct 02 17:18:52 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;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 Oct 02 06:33:15 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;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;Thu Oct 01 18:33:54 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;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;Thu Oct 01 18:19:34 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;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;Thu Oct 01 17:35:09 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;Thu Oct 01 17:33:08 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;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;Thu Oct 01 05:57:15 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;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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2 hours ago

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cheeseplus

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7 Messages

Maybe relevant, maybe not: it does seem like the time of day and network congestion may be related

This morning the connection crashed out 4x even with application bandwidth caps but around noon I was able to complete several large downloads which had been problematic. 

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24 minutes ago

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cheeseplus

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7 Messages

21 days ago

A tech came out yesterday, undid the splitter and attentuator that the last tech put in place, and then reactivated my modem. We had less than 24 hours of stability and had to reset the modem after it lost connection this morning under barely any load.

I'm currently evaluating changing out the modem out for a Netgear CM3000 or dropping back to our old S33 as I'm tired of having to reboot the modem and have yet to get Xfinity to check anything _outside_ the house. The S34 still reports the same errors as above so I do believe there is a tap/drop issue but at this point I care more about stable internet than proving this issue with another tech visit.

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user_0nhk9l

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4 Messages

I also have (had) the S34 modem with the same issues.  I swapped it out for a CM3000 and still receive the same T3 timeouts as with the S34.  I don't believe it's the modem either.

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19 days ago

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cheeseplus

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7 Messages

Although it sucks to hear you're experiencing similar issues it is good to get some confirmation that modem swap didn't change much. A CM3000 just arrived and I'll be giving it a try but remaining skeptical of the upstream connection.

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15 days ago

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cheeseplus

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15 days ago

Update, still on S34 modem after 2nd technician visit:

- we've lost connection pretty much everyday in early morning hours (same as before)

- connection also drops out under heavy load (also same as before)

CM3000 modem arrived and we'll be trying that out but I feel like this is going to keep happening until Xfinity actually checks the drop or further upstream.

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user_0nhk9l

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@cheeseplus​ It hasn't been any better for me.  Xfinity  just keeps refusing to acknowledge the problem is on their end.  How many of us have all posted the same questions/issues?  The fix is NEVER our equipment.  It's always theirs.

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10 days ago

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