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chewy75
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9 Messages

Wednesday, December 11th, 2024 11:08 PM

Netgear CM600 connection issues

I've been having connection issues with modem on and off for about 6 months. It usually happens when my router, or modem loses power and starts back up. My router is a asus RT-AX86U Pro running asuswrt-merlin firmware and my modem is a Netgear CM600

I spoke to support desk for xfinity and they said my line is clean and shows a healthy signal. They suggested I try manufacture support and they said that the critical errors needed to be reviewed by xfinity. so here i am.

Any help would be appreciated.

Note: I've already tried power cycling router and modem, I have no splitters and have good cables.  I even tried factory resetting the modem. 


Thanks

Checking on the cm600 logs I noticed that I only have 1 Upstream bonded channel locked, but should have more.

Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency
 
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 459000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enable BPI+
IP Provisioning Mode Honor MDD IPv6 only
 
<tabindex=-1>Downstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 5 459000000 Hz -0.1 dBmV 42.4 dB 0 0
2 Locked QAM256 22 561000000 Hz 0.3 dBmV 41.8 dB 0 0
3 Locked QAM256 23 567000000 Hz 0.3 dBmV 42.1 dB 0 0
4 Locked QAM256 24 573000000 Hz 0.6 dBmV 42.2 dB 1 0
5 Locked QAM256 1 435000000 Hz 0.4 dBmV 42.4 dB 0 0
6 Locked QAM256 2 441000000 Hz -0.2 dBmV 42.0 dB 0 0
7 Locked QAM256 3 447000000 Hz -0.7 dBmV 41.8 dB 0 0
8 Locked QAM256 4 453000000 Hz 0.6 dBmV 42.9 dB 0 0
9 Locked QAM256 6 465000000 Hz 0.4 dBmV 42.7 dB 0 0
10 Locked QAM256 7 471000000 Hz 0.6 dBmV 42.8 dB 0 0
11 Locked QAM256 8 477000000 Hz -0.4 dBmV 42.0 dB 0 0
12 Locked QAM256 9 483000000 Hz 0.6 dBmV 42.6 dB 0 0
13 Locked QAM256 10 489000000 Hz 0.1 dBmV 42.3 dB 0 0
14 Locked QAM256 11 495000000 Hz -0.1 dBmV 42.4 dB 0 0
15 Locked QAM256 12 501000000 Hz 0.7 dBmV 42.9 dB 0 0
16 Locked QAM256 13 507000000 Hz 0.3 dBmV 38.7 dB 0 0
17 Locked QAM256 14 513000000 Hz -0.4 dBmV 42.5 dB 0 0
18 Locked QAM256 15 519000000 Hz -0.5 dBmV 42.1 dB 0 0
19 Locked QAM256 16 525000000 Hz -1.0 dBmV 41.9 dB 0 0
20 Locked QAM256 17 531000000 Hz -0.4 dBmV 41.9 dB 0 0
21 Locked QAM256 18 537000000 Hz -0.5 dBmV 42.0 dB 0 0
22 Locked QAM256 19 543000000 Hz -0.5 dBmV 41.9 dB 0 0
23 Locked QAM256 20 549000000 Hz -0.1 dBmV 41.9 dB 0 0
24 Locked QAM256 21 555000000 Hz -0.2 dBmV 41.9 dB 1 0
 
<tabindex=-1>Upstream Bonded Channels</tabindex=-1>
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 57.0 dBmV
2 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
3 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
4 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

event log

Time Priority Description
2024-12-11, 12:49:18 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:48:29 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:48:23 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:47:34 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxxCM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:47:31 Critical (3) No UCDs Received - Timeout;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:47:11 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:46:26 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:46:22 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:49 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:27 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:23 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=xxxCMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:22 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:11 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:10 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:07 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:45:00 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:44:57 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:44:04 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:43:17 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:43:13 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:42:22 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:41:31 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxxCM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:41:24 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxxCMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:40:41 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:39:50 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:38:13 Critical (3) No UCDs Received - Timeout;;CM-MAC=xxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:37:56 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:37:51 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:37:43 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxx:d0;CMTS-MAC=xxxCM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:37:31 Critical (3) REG RSP not received;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:36:05 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:36:00 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:35:13 Critical (3) No UCDs Received - Timeout;;CM-MAC=xxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:34:56 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:34:51 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:34:03 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.0;CM-VER=3.0;
2024-12-11, 12:33:57 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:33:40 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxx;CMTS-MAC=xxxCM-QOS=1.1;CM-VER=3.0;
2024-12-11, 12:33:08 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=xxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6

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Accepted Solution

EG

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107.5K Messages

3 days ago

The upstream power is too high / out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the unbonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are 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 from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, etc.

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.


Good luck with it !

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chewy75

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i only have xfinity internet and no cable tv, so there are no splitters and cables are good.

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3 days ago

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EG

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107.5K Messages

@chewy75​ 

OK so if there is nothing more that can be done to improve the connection quality, then you'll need a tech visit as stated. 


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 up 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. And if the problem is found to be on their side of the demarcation point, there will not be any charge.

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.

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3 days ago

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chewy75

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9 Messages

OK thanks. So it's not the modem (even though it's need to be updated). I will call xfinity 

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2 days ago

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XfinityRay

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Thanks for your expert assistance, @EG! We are happy to get a visit set up for your service, @chewy75!

Please send us a direct message with your full name and complete service address to “Xfinity Support”. To do so, click on the direct messaging icon located at the top right of this forums page.

Here's the detailed steps to direct message us:
• Click "Sign In" if necessary
• Click the "Direct Message” icon (upper right corner of this page)
• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list
• Type your message in the text area near the bottom of the window
• Press Enter to send your message

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14 hours ago

EG

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107.5K Messages

3 days ago

Please redact all of the CM MAC and the CMTS MAC addresses from your error log entries for your privacy. They are considered to be personal information. The posting of personally identifiable information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publicly. It flagged your post as "Private".

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PSN890

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5 Messages

3 days ago

FYI, Comcast pulled the CM600 from its approved modems list.

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EG

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@PSN890​ That wouldn't stop it from still being grandfathered in. It's still connected.. The signal issue is quite clear.. 

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3 days ago

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chewy75

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9 Messages

12 hours ago

So xfinity tech came out today and traced my coaxial cable back to a splitter. My apartment complex is old and the splitter was hidden. To make it worse, the previous tenants set it up with the input/output cables reversed. That combined with my older modem is what was causing the issues.  The tech removed the splitter and my old router is now able to connect to 4 Upstream channels.

I'm also getting a new modem this weekend and went with a surfboard sb8200. 

Thanks everyone for the help and input. It's much appreciated.  Happy Holidays 

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PSN890

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Awesome! Happy Holidays. Thanks for keeping us updated.

Phil

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11 hours ago

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XfinityJorge

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chewy75 Thank you so much for the updateand for letting us know that everything is working better. If you need any help, please do not hesiate to contact us. Our team is always here to work with you. 

 

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11 hours ago

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EG

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@PSN890​ oyyyy.......

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9 hours ago

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EG

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@PSN890​ Oyyyy... 

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9 hours ago

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