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SYNC Timing Synchronization failure

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Frequent Visitor

SYNC Timing Synchronization failure

Good Morning

 

   I've been recently having problems with my internet connection and decided to start troubleshooting the issue. I currently using a MB7420 16x4 DOCSIS 3.0 Cable Modem approved by xFinity. First of all, I thought it was my router but after of making a series of test it appeared that eliminated it being the suspect of my problems. I decided to look into my cable modem and found these error message stating: "SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=00:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;". I have tried to investigate the error on xfinity's forums but it appears that a possible solution is either locked or the response is not viewable.  Is there anyone at Comcast/xfinity that can provide an update as to why I'm getting these errors and a possible way to fix this? Thanks 

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Gold Problem Solver

Re: SYNC Timing Synchronization failure

Please see Connection Troubleshooting Tips. Also please post your modem or gateway's signal information, especially downstream power levels and SNR, upstream power levels, and error log.

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Frequent Visitor

Re: SYNC Timing Synchronization failure

I've attached a file with the information you requested. I hope this helps.

 

Thanks 

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Gold Problem Solver

Re: SYNC Timing Synchronization failure

I had trouble reading the .xlsx file with my ancient copy of Excel. Is the following correct?

 

   Downstream Bonded Channels
   ChannelLock StatusModulationChannel IDFreq. (MHz)Pwr (dBmV)SNR (dB)CorrectedUncorrected
1LockedQAM25614171.340.71310
2LockedQAM25624230.440.222370
3LockedQAM25634290.840.335881412
4LockedQAM25644350.740.31520
5LockedQAM25654410.840.31470
6LockedQAM2566447140.41460
7LockedQAM25674531.440.61660
8LockedQAM25684591.840.71620
9LockedQAM25694651.540.61700
10LockedQAM256104711.440.51810
11LockedQAM256114771.640.51810
12LockedQAM256124830.640.21880
13LockedQAM256134890.440.11880
14LockedQAM256144950.139.91790
15LockedQAM25615519140.11930
16LockedQAM256165251402080
Total      40510412

 

Upstream Bonded Channels
 ChannelLock StatusChannel TypeChannel IDSymb. Rate (Ksym/sec)Freq. (MHz)Pwr (dBmV)
1LockedATDMA2512023.737.5
2LockedATDMA3512030.137.8
3LockedATDMA4512036.537.5
4Not LockedUnknown0000

 

Event Log  
 Time  Priority  Description 
Mon Mar 30 07:10:39 2020  Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Mar 30 07:10:41 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Mon Apr 20 05:38:12 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 05:38:18 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 05:39:52 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 05:41:56 2020  Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:31:43 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:31:49 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:34:37 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:34:37 2020  Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:34:57 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:34:57 2020  Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:35:13 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:35:13 2020  Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Mon Apr 20 07:35:15 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.0;CM-VER=3.0; 
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6 
Tue Apr 21 11:41:19 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Tue Apr 21 11:41:22 2020  Warning (5) MDD message timeout;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Tue Apr 21 11:43:22 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Tue Apr 21 11:43:22 2020  Warning (5) MDD message timeout;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Tue Apr 21 11:45:40 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Tue Apr 21 11:45:40 2020  Warning (5) MDD message timeout;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 
Tue Apr 21 11:46:09 2020  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:46:fd:d1;CMTS-MAC=00:01:5c:ad:ec:70;CM-QOS=1.1;CM-VER=3.0; 

 

The power levels and downstream SNR look OK, but the error log indicates a problem. You may need to have a Comcast tech take a look, if you can persuade to come out. Call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. If they can't fix the problem remotely (that's unlikely), insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit unless you have their Service Protection Plan (https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device, or anything outside your home, you shouldn't be charged.

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Frequent Visitor

Re: SYNC Timing Synchronization failure

Thanks. I will do that.