CM500-100NAS - Loosing connection - SYNC Timing Synchronization failure

[Florida712]

Hello All,
I have a CM500-100NAS, which while a couple of years old worked flawlessly until about 2 weeks ago, my firmware seems up to date as V1.01.12.

I have since experienced many many dropped connections, I can see that it is on my modem side using Apple Airport utility.
I had Xfinity out here yesterday and they measured and all is ok from their side, they tightened some connections but couldnt see anything really. The technician noted that I have part of the old cable R59 in between the ISP box and my modem. (But this has not been an issue for the last 3 years we have been living here).

After resetting the modem and the router I have now looked into the error logs of the modem and find this:

It is a mix of SYNCH Timing failure, where the date shows as 1970 .... and Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out.

Any advise would be highly appreciated.

Thanks a lot

Time Priority Description 1970-1-1, 00:00:30 Notice (6) Honoring MDD; IP provisioning mode = IPv6 1970-1-1, 00:00:22 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 2020-2-9, 13:50:38 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:50:07 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:50:06 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:49:34 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:49:33 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:49:02 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:49:00 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:48:44 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:48:39 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 2020-2-9, 13:47:22 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:01:5c:a2:fe:54;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:11:25 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:45 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:45 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:26 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:25 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:17 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:16 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:14 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:14 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:09 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:08 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:06 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:05 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:04 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:04 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:02 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:06:01 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:59 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:59 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:58 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:57 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:54 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:53 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:53 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:52 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:46 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:43 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:05:43 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:8d:1a:40;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;

[plemans]

Also take a screen snip of your modems connections page. 

This tells us signal quality etc. 

One thing to keep in mind is that xfinity techs aren't known for being the best or checking in the home. they tend to connect right where the coax enters and base their readings from there. They charge for anything fixed in the home. So connect the modem right where the coax enters. sometimes issues with coax runs in the home, splitters, etc can cause issues.

so directly connect, take the screen snip, and see how it runs. 

[FURRYe38]

Have the ISP check the signal and line quality UP to the modem. 
Be sure there are not coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 

---

@Florida712 wrote:

Hello All,
I have a CM500-100NAS, which while a couple of years old worked flawlessly until about 2 weeks ago, my firmware seems up to date as V1.01.12.

I have since experienced many many dropped connections, I can see that it is on my modem side using Apple Airport utility.
I had Xfinity out here yesterday and they measured and all is ok from their side, they tightened some connections but couldnt see anything really. The technician noted that I have part of the old cable R59 in between the ISP box and my modem. (But this has not been an issue for the last 3 years we have been living here).

After resetting the modem and the router I have now looked into the error logs of the modem and find this:

It is a mix of SYNCH Timing failure, where the date shows as 1970 .... and Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out.

Any advise would be highly appreciated.

Thanks a lot