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Continuous T3/T4 errors, connection dropping

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Regular Visitor

Continuous T3/T4 errors, connection dropping

Hello,

 

After 7+ months of good quality service, my internet became unusable last week, with network dropping every ~10 minutes or so and the modem showing multiple T3 and T4 errors. It's clear that the modem error are causing the network drop -- the log entries appear immediately as the network resets.

 

I've tried calling Xfinity Support, but the representative shows no interest in helping beyond telling me to run the diagnostics in the My Account app, or telling me to call the modem/router manufacturer(!). It's extremely frustrating as my current ability to work from home is now in jeopardy.

 

I have made no changes to the local hardware or firmware configs. No splitters or other connections in line. Wifi LAN is working fine -- it's the external connection that keeps dropping.

 

Modem/router: Netgear C7000v2 (new in Sep 2019)

Firmware version: V1.03.01

 

i'm posting in this forum in hopes of getting some kind of assessment on the quality of my connection upstream from my home. 

 

Modem logs posted below.

 

Many thanks for any response.

 

Bob

 

Time Priority Description
2020-4-20, 13:16:58 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:16:50 Warning (5) Dynamic Range Window violation
2020-4-20, 13:16:45 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:16:30 Warning (5) Dynamic Range Window violation
2020-4-20, 13:16:25 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:16:12 Warning (5) Dynamic Range Window violation
2020-4-20, 13:13:09 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2020-4-20, 13:12:55 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.0;CM-VER=3.0;
2020-4-20, 13:12:42 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:12:39 Warning (5) Dynamic Range Window violation
2020-4-20, 13:12:35 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:12:19 Warning (5) Dynamic Range Window violation
2020-4-20, 13:12:15 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:12:11 Warning (5) Dynamic Range Window violation
2020-4-20, 13:12:10 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:12:07 Warning (5) Dynamic Range Window violation
2020-4-20, 13:12:06 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:12:06 Warning (5) Dynamic Range Window violation
2020-4-20, 13:12:05 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:12:02 Warning (5) Dynamic Range Window violation
2020-4-20, 13:12:01 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:12:01 Warning (5) Dynamic Range Window violation
2020-4-20, 13:11:59 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:11:59 Warning (5) Dynamic Range Window violation
2020-4-20, 13:11:57 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:11:54 Warning (5) Dynamic Range Window violation
2020-4-20, 13:11:52 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:11:43 Warning (5) Dynamic Range Window violation
2020-4-20, 13:11:39 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:10:59 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2020-4-20, 13:10:21 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.0;CM-VER=3.0;
2020-4-20, 13:10:09 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:09:55 Warning (5) Dynamic Range Window violation
2020-4-20, 13:09:42 Warning (5) Unicast DSID PSN startup error
2020-4-20, 13:09:36 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:09:36 Warning (5) Dynamic Range Window violation
2020-4-20, 13:09:36 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:09:36 Warning (5) Dynamic Range Window violation
2020-4-20, 13:09:36 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=28:80:88:0c:52:40;CMTS-MAC=2c:86:d2:88:ee:42;CM-QOS=1.1;CM-VER=3.0;
2020-4-20, 13:09:33 Warning (5) Dynamic Range Window violation

 

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 513000000 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 9 513000000 Hz -2 dBmV 38.3 dB 126 229
2 Locked QAM256 13 543000000 Hz -2.5 dBmV 38.3 dB 8240 4934
3 Locked QAM256 14 549000000 Hz -2.6 dBmV 38.4 dB 8117 4891
4 Locked QAM256 15 555000000 Hz -2.7 dBmV 38.5 dB 8122 4623
5 Locked QAM256 16 561000000 Hz -2.9 dBmV 37.6 dB 7967 4427
6 Locked QAM256 17 567000000 Hz -3.1 dBmV 38.4 dB 7841 4287
7 Locked QAM256 18 573000000 Hz -3.1 dBmV 38.2 dB 7574 4184
8 Locked QAM256 19 579000000 Hz -3.2 dBmV 38 dB 7504 4148
9 Locked QAM256 20 585000000 Hz -3.2 dBmV 37.5 dB 7616 3818
10 Locked QAM256 21 591000000 Hz -3.3 dBmV 37.3 dB 7636 3930
11 Locked QAM256 22 597000000 Hz -3.4 dBmV 37.2 dB 7493 3513
12 Locked QAM256 23 603000000 Hz -3.5 dBmV 37.1 dB 7041 4040
13 Locked QAM256 24 609000000 Hz -3.7 dBmV 37.1 dB 7338 3295
14 Locked QAM256 1 459000000 Hz -1.3 dBmV 38.7 dB 182 119
15 Locked QAM256 2 465000000 Hz -1.4 dBmV 38.8 dB 137 181
16 Locked QAM256 3 471000000 Hz -1.4 dBmV 39.1 dB 151 211
17 Locked QAM256 4 477000000 Hz -1.8 dBmV 38.2 dB 0 0
18 Locked QAM256 5 483000000 Hz -1.9 dBmV 38.2 dB 0 0
19 Locked QAM256 6 489000000 Hz -2.1 dBmV 38.2 dB 0 0
20 Locked QAM256 7 495000000 Hz -2.3 dBmV 37.8 dB 0 0
21 Locked QAM256 8 507000000 Hz -2.3 dBmV 37.7 dB 0 0
22 Locked QAM256 10 519000000 Hz -2.6 dBmV 37.6 dB 0 0
23 Locked QAM256 11 525000000 Hz -2.8 dBmV 37.1 dB 0 0
24 Locked QAM256 12 531000000 Hz -2.8 dBmV 37.5 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 36500000 Hz 39.9 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 30100000 Hz 39.7 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 17300000 Hz 39.8 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 23700000 Hz 38.7 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 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
 
Extended Upstream Transmit Power
Current System Time:Mon Apr 20 13:39:20 2020
System Up Time:02:50:29
Highlighted
Regular Visitor

Re: Continuous T3/T4 errors, connection dropping

Still getting constant disconnects -- what other information can I share to get a response or assist with troubleshooting?

 

Thanks in advance.

Highlighted
Expert

Re: Continuous T3/T4 errors, connection dropping

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) 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 !



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
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Highlighted
Regular Visitor

Re: Continuous T3/T4 errors, connection dropping

Thanks very much @EG !

 

I very much appreciate your response and offer to assist.

Highlighted
Expert

Re: Continuous T3/T4 errors, connection dropping

Quite welcome !



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Official Employee

Re: Continuous T3/T4 errors, connection dropping

Hi 2wheelsburning. We appreciate you visiting and posting on our Forums. I can assist with further troubleshooting your connectivity issues. I'd like to start with polling our CMTS for real-time and historical RF signal reports from your modem. I can also check your local Node/Plant for any degradation or error reports. Please send me a private message and include your full name so I can access your equipment. 


I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Regular Visitor

Re: Continuous T3/T4 errors, connection dropping

PM sent, thanks @ComcastJoeTru for your response and offer to help.