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T3/T4 Critical Timeout Errors causing latency spikes for MONTHS potentially?

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T3/T4 Critical Timeout Errors causing latency spikes for MONTHS potentially?

I have a CM500 and I'd say sometime around January I started getting these very strange spikes in connection. Sometimes they last for a few seconds, sometimes they last for a few minutes. I never FULLY disconnect from the internet and I've had multiple tech guys come out here and one of them said that it could potentially be something to do with the outside cables. Today I had the most recent tech out here and he told me the cables all look good on the outside and it could potentially just be the modem or router since the cables look fine. This issue has been driving me INSANE so if anyone has any clue what could be causing it I would appreciate it SO much. I just placed an order for a new modem which will be the CM700 but I really don't think it's the modem causing the issues but it's what Comcast told me. If someone could figure this out for me I would be EXTREMELY grateful. 

 

This is a picture of a website I use to monitor my connection when I see it spiking, it's very basic but it lets me know when it happens. The picture shown here is the time when my connection is spiking. This next picture shows when my connection is fine right after a spike and sometimes stays stable for awhile before spiking again. I also made sure to ping Comcasts IP using CMD to check the times and during a spike it very clearly shows spikes of up to 200+ms responses.

 

Startup Procedure
ProcedureStatusComment
Acquire Downstream Channel471000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
SecurityEnabledBPI+
IP Provisioning ModeHonor MDDhonorMdd(4)
 
Downstream Bonded Channels
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUncorrectables
1LockedQAM2569471000000 Hz-5.2 dBmV39 dB148665
2LockedQAM2561423000000 Hz-4.6 dBmV39.3 dB153735
3LockedQAM2562429000000 Hz-4.8 dBmV39.3 dB159731
4LockedQAM2563435000000 Hz-4.9 dBmV39.2 dB172662
5LockedQAM2564441000000 Hz-4.8 dBmV39.2 dB149654
6LockedQAM2565447000000 Hz-4.6 dBmV39.3 dB123678
7LockedQAM2566453000000 Hz-4.7 dBmV39.3 dB125678
8LockedQAM2567459000000 Hz-5 dBmV39.1 dB137672
9LockedQAM2568465000000 Hz-5.2 dBmV39.1 dB144659
10LockedQAM25610477000000 Hz-5 dBmV39 dB157658
11LockedQAM25611483000000 Hz-4.9 dBmV38.7 dB163665
12LockedQAM25612489000000 Hz-5 dBmV38.7 dB148670
13LockedQAM25613495000000 Hz-5.3 dBmV38.9 dB180643
14LockedQAM25614507000000 Hz-5.7 dBmV37.9 dB176676
15LockedQAM25615513000000 Hz-5.8 dBmV38.4 dB160685
16LockedQAM25616519000000 Hz-5.9 dBmV38.5 dB182665
 
Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA35120 Ksym/sec22800000 Hz43.8 dBmV
2LockedATDMA15120 Ksym/sec35600000 Hz43.8 dBmV
3LockedATDMA25120 Ksym/sec29200000 Hz43.8 dBmV
4LockedATDMA45120 Ksym/sec16400000 Hz43.8 dBmV
 
 
 
 
TimePriorityDescription
2020-9-11, 08:37:47Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:25:06Notice (6)Honoring MDD; IP provisioning mode = IPv6
2020-9-11, 08:24:41Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-9-11, 08:24:40Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-9-11, 08:24:39Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-9-11, 08:24:38Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-9-11, 08:12:38Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-9-11, 08:12:38Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-9-11, 08:12:36Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:12:17Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:12:16Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:11:57Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:11:56Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:11:37Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:11:36Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:10:51Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:10:50Warning (5)MDD message timeout;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-11, 08:10:47Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-8, 22:28:28Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
2020-9-8, 22:23:48Warning (5)MDD message timeout;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
1970-1-1, 00:00:34Notice (6)Honoring MDD; IP provisioning mode = IPv6
1970-1-1, 00:00:22Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-9-8, 22:14:02Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
1970-1-1, 00:00:22Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-23, 02:54:03Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.1;CM-VER=3.0;
1970-1-1, 00:00:28Critical (3)No Ranging Response received - T3 time-out;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:20:15Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:20:14Critical (3)No UCDs Received - Timeout;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:19:57Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:19:56Critical (3)No UCDs Received - Timeout;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:19:39Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:19:38Critical (3)No UCDs Received - Timeout;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:19:20Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:19:19Critical (3)Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:18:55Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:18:54Critical (3)Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=94:d4:69:54:cc:ea;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:18:43Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:18:42Critical (3)No UCDs Received - Timeout;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:18:25Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-8-19, 08:18:24Critical (3)No UCDs Received - Timeout;;CM-MAC=08:36:c9:4f:f7:78;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;

 

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Official Employee

Re: T3/T4 Critical Timeout Errors causing latency spikes for MONTHS potentially?

Greetings, @Tropial! I appreciate you taking the time to reach out to us here on the forums. I hope you are having an amazing day! I apologize to hear of the issues you are having with your internet connection. I know how important it is to have a reliable connection these days. I work from home myself and rely heavily on my internet connection. I would like to see what we can do for you. Since you already sent a PM, I will continue to assist you through there.


I am an Official Comcast Employee.
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