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Constanly Losing Connection

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Constanly Losing Connection

All day yesterday and today, I have been losing my connection for a couple of minutes at a time.  The log from my SB6121 modem shows numerous errors:

 

Apr 21 2020 09:31:11 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 09:30:31 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 09:28:14 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 09:27:30 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 09:13:02 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 09:12:17 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 09:10:03 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 09:09:17 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:51:53 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:51:12 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:34:54 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:33:51 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:31:33 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:30:52 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:15:50 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:15:09 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:12:50 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:12:11 3-Critical T05.0 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Apr 21 2020 08:02:17 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:02:22 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=a4:7a:a4:ef:25:3b;CMTS-MAC=00:01:5c:a8:0a:52;CM-QOS=1.1;CM-VER=3.0;

 

My modem has been power-cycled and reset many times, and I went outside this morning and disconnected the cable, cleaned the connections, and put it back, but nothing has helped.  I have wasted hours attempting to reach someone at Comcast who might be able to help me, but they have eliminated cutomer service and tech support, so I don't know what to do.  Until another ISP becomes available in my area, I am stuck with Comcast.  Is there any way to get a techinican (if Comcast still employs any) to check the line?

 

Thank You

 

 

Larry


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Re: Constanly Losing Connection

Please see Connection Troubleshooting Tips. and post your modem's signal information, especially downstream power levels and SNR, and upstream power levels.

 

Note that Comcast no longer supports the 6121, although that's probably not the cause of the problem you are seeing. See https://www.xfinity.com/support/devices/. You'll have to click "Show Unsupported Devices" after entering "6121" in the search box.