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Intermittent Modem Signal Loss (T3, T4, Timing Synchronizaiton Failure, No Unicast Maintenance, etc.

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Intermittent Modem Signal Loss (T3, T4, Timing Synchronizaiton Failure, No Unicast Maintenance, etc.

I'm experiencing intermittent signal loss from my modem (CM500-100NAS). The problem started a few months ago and has been increasing in frequency. It now occurs about several times a day and the modem experiences signal failure for a few minutes or longer. I've tried everything tech support told me to do without any effect and the last time I called they told me that they have no idea what the problem is or how to fix it.

 

I found a similar sounding issue on another board (https://forums.xfinity.com/t5/Your-Home-Network/Signal-loss-RNG-RSP-CCAP-T3-Timeout-etc/td-p/3255229) but it was escalated to a comcast rep and addressed offline so I'm not sure what I can do.

 

Any help is appreciated, thanks!

 

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 441000000 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 12 441000000 Hz -4.1 dBmV 39.9 dB 2683 239
2 Locked QAM256 13 447000000 Hz -4.4 dBmV 39.9 dB 3840 839
3 Locked QAM256 14 453000000 Hz -4.5 dBmV 39.7 dB 3242 2540
4 Locked QAM256 15 459000000 Hz -4.8 dBmV 39.8 dB 937 708
5 Locked QAM256 16 465000000 Hz -5 dBmV 39.7 dB 2338 962
6 Locked QAM256 17 471000000 Hz -4.9 dBmV 39.8 dB 1207 1399
7 Locked QAM256 18 477000000 Hz -5.2 dBmV 39.6 dB 981 891
8 Locked QAM256 19 483000000 Hz -4.8 dBmV 39.7 dB 1781 728
9 Locked QAM256 20 489000000 Hz -4.7 dBmV 37 dB 1348 843
10 Locked QAM256 21 495000000 Hz -4 dBmV 38.4 dB 901 858
11 Locked QAM256 22 501000000 Hz -4.2 dBmV 35.2 dB 22060 10191
12 Locked QAM256 23 507000000 Hz -3.9 dBmV 37.5 dB 868 62
13 Locked QAM256 24 513000000 Hz -4 dBmV 39.9 dB 690 865
14 Locked QAM256 25 519000000 Hz -3.6 dBmV 40.1 dB 681 804
15 Locked QAM256 26 525000000 Hz -3.9 dBmV 37.3 dB 962 1057
16 Locked QAM256 27 531000000 Hz -3.7 dBmV 38.2 dB 716 435
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 3 5120 Ksym/sec 30100000 Hz 54.8 dBmV
2 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
3 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
4 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

 

 

Time Priority Description
2019-9-7, 04:13:29 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 04:13:15 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 04:13:09 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 04:12:50 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 04:12:38 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-7, 03:44:33 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 03:44:22 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 03:44:13 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-6, 04:55:34 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-6, 04:55:23 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 21:31:30 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-5, 21:31:21 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-5, 21:31:15 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-5, 21:30:54 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-5, 21:30:42 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 21:15:57 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-5, 21:15:44 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 19:58:11 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-5, 19:57:59 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 19:53:46 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 12:29:59 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-5, 12:26:07 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-5, 12:25:59 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 12:21:45 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 12:21:45 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-5, 12:18:33 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-4, 14:55:26 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-4, 14:55:19 Warning (5) B-INIT-RNG Failure - Retries exceeded;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-4, 14:49:09 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-4, 14:49:01 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-4, 05:53:51 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-4, 05:53:38 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-4, 05:29:47 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-4, 05:29:34 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-4, 05:11:44 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-4, 05:11:32 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-4, 04:45:41 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-4, 04:45:27 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-4, 02:56:46 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-4, 02:56:35 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
Diamond Problem Solver

Re: Intermittent Modem Signal Loss (T3, T4, Timing Synchronizaiton Failure, No Unicast Maintenance,

You only have 1 upstream channel, instead of 3 possibly 4 depending on location. The one channel that you do have is too high and out of spec. You need to drop it by about 7db, see if there’s any extra splitters you can remove or rearrange to lower the upstream and possibly gain those other upstream channels back. If you can’t, you’ll probably need a tech out to troubleshoot further

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Regular Visitor

Re: Intermittent Modem Signal Loss (T3, T4, Timing Synchronizaiton Failure, No Unicast Maintenance,

Thanks for pointing that out, this is actually the first time I've seen it have less than four upstream channels, but they are normally at 54 dBmV. Right now and normally the upstream channels are:

 

Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 1 5120 Ksym/sec 17300000 Hz 54 dBmV
2 Locked ATDMA 2 5120 Ksym/sec 23700000 Hz 54 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 30100000 Hz 54 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 36500000 Hz 54 dBmV
 
Extended Upstream Transmit Power

Enable Extended Upstream Transmit Power

 

I lost signal again right as I was posting, could I have been losing upstream channels slowly building up to a signal loss?

 

The event log for the latest outage is:

 

Time Priority Description
2019-9-7, 09:35:17 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 09:35:06 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.1;CM-VER=3.0;
2019-9-7, 09:13:30 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 09:13:22 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:13:21 Critical (3) No UCDs Received - Timeout;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:13:11 Warning (5) Lost MDD Timeout;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:13:04 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:13:03 Critical (3) No UCDs Received - Timeout;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:12:53 Warning (5) Lost MDD Timeout;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:12:46 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:12:45 Critical (3) No UCDs Received - Timeout;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:12:35 Warning (5) Lost MDD Timeout;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:12:28 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:12:11 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 09:11:40 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:11:34 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:11:33 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:11:32 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:11:29 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:11:28 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:11:08 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 09:10:39 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:10:25 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:10:25 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:10:25 Critical (3) No UCDs Received - Timeout;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:10:15 Warning (5) Lost MDD Timeout;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:10:07 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:10:06 Critical (3) No UCDs Received - Timeout;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:09:56 Warning (5) Lost MDD Timeout;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:09:49 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:09:48 Critical (3) No UCDs Received - Timeout;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:09:38 Warning (5) Lost MDD Timeout;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:09:31 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:08:16 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-9-7, 09:07:43 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:07:34 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:07:32 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:07:32 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:07:30 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:59:c0:fe:92:00;CMTS-MAC=00:01:5c:b6:de:92;CM-QOS=1.0;CM-VER=3.0;
2019-9-7, 09:07:14 Notice (6) Honoring MDD; IP provisioning mode = IPv6

 

The "No UCDs received" and "Lost MDD Timeout" are less common and weren't in the previous event log.

 

I'll try looking for any splitters that can be removed or adjusted and see if I can lower the upstream signal. Is there anything else I should try or check before having a technician come out?

 

Thanks for your help!

Diamond Problem Solver

Re: Intermittent Modem Signal Loss (T3, T4, Timing Synchronizaiton Failure, No Unicast Maintenance,

Test your modem at the ground block or before any splitters so you have something to compare your earlier signal levels with. Easier to point to an inside or outside issue.

I am a Retired Official Comcast Employee
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