U

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3 Messages

Sun, Apr 11, 2021 11:41 PM

Intermittent Connection Drops with T3 and T4 Timeouts

Good Evening. I wanted to post this to the forums in the hope to get a more experienced opinion. I moved to a new apartment during the pandemic and have since been getting really bad internet service. During the first few months, it was tolerable but now I get connection drops multiple times during the day and in most cases, I have to restart the modem/router. It is at a point where I simply am not able to work from home.

I have received the following responses from Xfinity support which haven't been any help,

  • On the first occasion, customer service mentioned that there was maintenance in our area and that service disruption was temporary.
  • On the second occasion, customer service said they had to resend a signal to the modem. They were confident that this was the issue and said there was no need for escalation.
  • On the third occasion, I had to work really hard to get a technician onsite. The technician put a new splitter as an optimization but he said the main issue was with my Netgear Router. Although slightly disappointed, I was actually happy as it seemed like logical troubleshooting as opposed to just being asked to power cycle my devices like with customer service on phone. 

I swapped out my Netgear Router plus Motorola Modem for an Arris SurfBoard SBG6580 Modem+Router combo. Unsurprisingly, the problem still persists. I am posting this with some logs hoping someone can point me in the right direction. I do see a lot of Critical errors with T3 and T4 timeouts and from a little research online it seems something is definitely wrong here.


Thu Apr 08 12:26:08 2021 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 12:26:08 2021 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 12:26:07 2021 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 10:29:53 2021 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 10:29:53 2021 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 10:29:53 2021 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 10:11:06 2021 Notice (6) TLV-11 - unrecognized OID;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6
Time Not Established Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.0;CM-VER=3.0;
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Time Not Established Notice (6) T4 No Station Maint Timeout - Reinitialize MAC...
Time Not Established Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.0;CM-VER=3.0;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Time Not Established Notice (6) WiFi Interface [wl0] set to Channel 1 (Side-Band Channel:N/A) - Reason:INIT
Thu Apr 08 10:07:50 2021 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 10:03:30 2021 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 07:30:22 2021 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 07:30:22 2021 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 07:30:21 2021 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 07:30:21 2021 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 07:30:21 2021 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 08 07:30:20 2021 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:96:84:be:37:37;CMTS-MAC=00:01:5c:af:82:52;CM-QOS=1.1;CM-VER=3.0;

Modem/Router Combo Model: ARRIS SURFboard SBG6580
https://www.amazon.com/ARRIS-SURFboard-SBG6580-DOCSIS-2-4Ghz/dp/B0040IUI46 

 

This post was escalated on April 12, 2021 by EG

Responses

EG

Expert

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86.6K Messages

1 m ago

Please also post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.

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Visitor

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3 Messages

1 m ago

@EG Attached below are the requested numbers,
Let me know if I am missing anything - Appreciate your help.

Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Corrected Uncorrectables
1 Locked QAM256 17 621000000 Hz 2.4 dBmV 41.2 dB 16405 26152
2 Locked QAM256 18 627000000 Hz 2.5 dBmV 41.4 dB 56015 23855
3 Locked QAM256 19 633000000 Hz 2.1 dBmV 40.4 dB 19782 29487
4 Locked QAM256 20 639000000 Hz 1.5 dBmV 40.9 dB 99696 21938
5 Locked QAM256 21 645000000 Hz 1.5 dBmV 40.4 dB 18617 30559
6 Locked QAM256 22 651000000 Hz 2.2 dBmV 42.0 dB 15740 25377
7 Locked QAM256 23 657000000 Hz 1.1 dBmV 41.4 dB 18097 26686
8 Locked QAM256 24 663000000 Hz 1.5 dBmV 41.4 dB 17466 28052

Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 42.3 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 35600000 Hz 44.0 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29200000 Hz 42.5 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 16400000 Hz 42.0 dBmV

Official Employee

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165 Messages

Good morning, @user_247d06. I know how frustrating internet issues can be. I rely on mine for everything! I'd love to help and look further into this for you. @EG Thank you for your assistance with this as well! 

 

@user_247d06, can you please send me a PM with your name and address? To send a private message, please click on the chat icon on the top right next to the bell. Please make sure to send the message to our singular handle "Xfinity Support" and we will get back to you ASAP.

 

 

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EG

Expert

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86.6K Messages

1 m ago

The signal stats are o/k but the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) /  an upstream channel-return path impairment somewhere.


There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !

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Visitor

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3 Messages

1 m ago

@ComcastKorie I have PMed you the details as requested.

@EG Thank you for escalating the issue, I hope they are able to poll additional information and figure out the issue. Do let me know if I can provide any more information. Will be waiting for a reply!

EG

Expert

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86.6K Messages

1 m ago

My pleasure ! :-)

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