Community Forum

SYNC Timing Synchronization Failure, T3 timouts, Critical (3) Loss of connection

Highlighted
New Poster

SYNC Timing Synchronization Failure, T3 timouts, Critical (3) Loss of connection

I regularly lose my connection and have to reboot the modem/router (Archer CR700), it's very frustrating. Here's my recent system log and connection status info:

 

Time Priority Description

Time Not EstablishedNotice (6)Honoring MDD; IP provisioning mode = IPv6
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.0;CM-VER=3.0;
Mon Oct 05 10:43:50 2020Critical (3)SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.1;CM-VER=3.0;
Mon Oct 05 10:35:32 2020Critical (3)SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.1;CM-VER=3.0;
Mon Oct 05 10:35:30 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QO...
Sun Oct 04 12:32:05 2020Critical (3)SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.1;CM-VER=3.0;
Sun Oct 04 07:47:12 2020Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;...
Sat Oct 03 18:28:49 2020Critical (3)SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.1;CM-VER=3.0;
Sat Oct 03 15:33:58 2020Critical (3)SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=c0:25:e9:35:71:84;CMTS-M...
Sat Oct 03 15:33:46 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QO...
Sat Oct 03 14:49:04 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QO...
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=00:00:00:00:00:00;CM-QO...
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=00:00:00:00:00:00;CM-QO...
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=00:00:00:00:00:00;CM-QO...
Time Not EstablishedCritical (3)

No Ranging Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.0;CM-VER=3.0;

 

Time Not EstablishedCritical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c0...
Time Not EstablishedCritical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;...
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.0;CM-VER=3.0;
Time Not EstablishedCritical (3)No UCDs Received - Timeout;;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=00:00:00:00...
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=00:00:00:00:00:00;CM-QO...
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.0;CM-VER=3.0;
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.0;CM-VER=3.0;
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QOS=1.0;CM-VER=3.0;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=00:00:00:00...
Thu Oct 01 05:32:15 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QO...
Thu Oct 01 05:32:13 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15...
Thu Oct 01 05:32:12 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QO...
Thu Oct 01 05:32:07 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15...
Thu Oct 01 05:32:04 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15...
 
Thu Oct 01 05:32:03 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15:c2:42;CM-QO...Thu Oct 01 05:32:01 2020Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c0:25:e9:35:71:84;CMTS-MAC=2c:0b:e9:15...
 
 
Downstream Bonded Channels

Channel Status Modulation Channel ID Frequency Power SNR
1LockedQAM25629633000000 Hz-7.2 dBmV38.3 dB
2LockedQAM25617561000000 Hz-6.9 dBmV37.0 dB
3LockedQAM25618567000000 Hz-7.0 dBmV37.1 dB
4LockedQAM25619573000000 Hz-6.8 dBmV38.9 dB
5LockedQAM25620579000000 Hz-6.6 dBmV38.8 dB
6LockedQAM25621585000000 Hz-6.5 dBmV38.9 dB
7LockedQAM25622591000000 Hz-7.8 dBmV38.2 dB
8LockedQAM25623597000000 Hz-7.9 dBmV34.2 dB
9LockedQAM25624603000000 Hz-8.2 dBmV34.8 dB
10LockedQAM25625609000000 Hz-8.1 dBmV38.1 dB
11LockedQAM25626615000000 Hz-7.6 dBmV38.5 dB
12LockedQAM25627621000000 Hz-7.9 dBmV37.3 dB
13LockedQAM25628627000000 Hz-7.0 dBmV36.8 dB
14LockedQAM25630639000000 Hz-7.2 dBmV36.4 dB
15LockedQAM25631645000000 Hz-7.8 dBmV38.3 dB
16LockedQAM25632651000000 Hz-7.6 dBmV38.4 dB

 

Upstream Bonded Channels

 

Channel Status Channel Type Channel ID Symbol Rate Frequency Power
1LockedATDMA95120 ksym/sec17300000 Hz47.8 dBmV
2LockedATDMA105120 ksym/sec23700000 Hz47.8 dBmV
3LockedATDMA115120 ksym/sec30100000 Hz47.8 dBmV
4LockedATDMA125120 ksym/sec36500000 Hz47.8 dBmV

 

I'd like to resolve this issue, any help is greatly appreciated.

Highlighted
Expert

Re: SYNC Timing Synchronization Failure, T3 timouts, Critical (3) Loss of connection

The downstream power is on the low side and it may be intermittently fluctuating even lower to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.



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!