Error logs for Netgear modem; limited connectivity

Please also post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.

What is the exact model number of the Netgear modem ?

HI. Thanks for following up.

I'm  confused, as this post seems to exist in 2 places now. 

Here are the last night's logs, plus power info (I don't see SNR in the readout anywhere).  I have a Netgear CM500 and have tried the toubleshooting multiple times.  And there is a single line from the outside of the house to the modem; no splitters.  Both ends have been replaced as far as I know.

2020-11-14, 19:26:31Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;

1970-1-1, 00:00:49Notice (6)Honoring MDD; IP provisioning mode = IPv6

1970-1-1, 00:00:27Critical (3)No Ranging Response received - T3 time-out;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:21Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

2020-11-14, 19:24:07Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

2020-11-14, 19:23:37Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:46Critical (3)No Ranging Response received - T3 time-out;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:37Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:36Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:25Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:25Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:21Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XXXXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

Downstream Bonded Channels

1 Locked QAM256 37 627000000 Hz 5.8 dBmV 40.9 dB 0 0

2 Locked QAM256 29 579000000 Hz 6 dBmV 41.4 dB 0 0

3 Locked QAM256 30 585000000 Hz 6 dBmV 41.3 dB 0 0

4 Locked QAM256 31 591000000 Hz 5.6 dBmV 41.2 dB 0 0

5 Locked QAM256 32 597000000 Hz 6 dBmV 41.4 dB 0 0

6 Locked QAM256 33 603000000 Hz 6.1 dBmV 41.4 dB 0 0

7 Locked QAM256 34 609000000 Hz 6.4 dBmV 41.6 dB 0 0

8 Locked QAM256 35 615000000 Hz 6.2 dBmV 41.4 dB 0 0

9 Locked QAM256 36 621000000 Hz 6 dBmV 41.1 dB 0 0

10 Locked QAM256 38 633000000 Hz 5.7 dBmV 40.8 dB 0 0

11 Locked QAM256 39 639000000 Hz 5.7 dBmV 40.6 dB 0 0

12 Locked QAM256 40 645000000 Hz 5.8 dBmV 40.8 dB 0 0

13 Locked QAM256 41 651000000 Hz 6.2 dBmV 41.1 dB 0 0

14 Locked QAM256 42 657000000 Hz 6.1 dBmV 40.9 dB 0 0

15 Locked QAM256 43 663000000 Hz 6.2 dBmV 40.9 dB 0 0

16 Locked QAM256 44 669000000 Hz 6 dBmV 40.7 dB 0 0

Upstream Bonded Channels

1 Locked ATDMA 4 5120 Ksym/sec 16400000 Hz 41.5 dBmV

2 Locked ATDMA 1 5120 Ksym/sec 35600000 Hz 41.5 dBmV

3 Locked ATDMA 2 5120 Ksym/sec 29200000 Hz 41.5 dBmV

4 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 41.5 dBmV

The stats (including the SNR's) are o/k. 

For a test, does a computer / device hardwired directly to the Netgear router / gateway device with an ethernet cable have the same problem ?

With this test, we are trying to isolate this from being either a WiFi-only problem or a problem with the general connection to the Comcast system which would of course affect both. It's a good first step of troubleshooting before we proceed any further.

Thanks for getting back to me.  I'm familiar with this step and the answer is a peculiar one.

After each of the two techs visited, I got good, normal speed when hardwired from laptop to modem--until it started acting up again.  Once the issues return, the hardwire doesn't work for internet.  My computer (Mac Mojave) shows "self-assigned IP address" and "cannot connect to the internet."

In this state, the hardwire internet does not work through the router, either, but I do get spotty WiFi (spotty meaning: some devices don't get internet--even though they are "connected," some websites won't load while others do, sometimes 2GHz works, and sometimes it's 5GHz that works.)

I use a (Linksys EA7500) router.

I also purchased a TP-Link Archer A8.  That router does not show an active internet signal light at all (orange vs. green).

Tech visits:

1- replaced line filter at house, replaced coax end at the modem (worked correctly for 3-4 days)

2- ran line from different pole (per their policy--supposed to come from same pole as power), replaced box, as the original one had deteriorated and was allowing water in. (worked correctly for 1 hour)

Hello @EG ,

I've tried following up twice, but see the posts were removed each time.  If that is a violation of post rules, please advise.

As you can imagine, after 4 days, I am eager to hear back, even if the response suggests I need to look elsewhere for answers.

Thanks again for your time.

Sounds like there are a few different things going on. Perhaps it would be best to get the techs re-involved until it is fixed properly. 

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.
Good luck !

Cheers, thatnks for the reply.  I have them on their way - 3rd visit. 

I even rented one of their modems to elimintae mine as the problem. 

Same symptoms. 

Thanks for your help!

Quite welcome ! Again, good luck with it !

Well, their modem: same problems, different logs. 

FW.LAN2SELF DROP

No progress with customer service; they just want to send another tech.