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Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

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Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

We have been experiencing Internet disconnects for months.  Here lately, it has become pretty intolerable.  We have had several technicians to the house.  Cabling is good.  Everything appears good.  The last tehcnician said it isn't the router.  He believes it is an Xfinity problem but nothing came of it.  Called  Xfinity again on Monday and they suggested we call Netgear.  For $50, Netgear suggested that we change the MTU size to 1492, Fragmentation Length to 2306 and CTS/RTS Threshold to 2307.  My wife changed the MTU size back to 1500 saying that 1492 was more appropriate for DSL.  She is still researching the other settings but thinks they may be more related to collisions with our own devices in our home.  Any assistance you can provide is much appreciated.  Please see settings and logs below.

 

Starting Frequency 561000000

 

Startup Procedure

Procedure Status Comment
Acquire Downstream Channel 561000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK ------------
Security Enable BPI+

 

Downstream Bonded channels

Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 28 561000000 Hz 10.9 dBmV 40.6 dB 354 448
2 Locked QAM256 24 537000000 Hz 10.7 dBmV 41.0 dB 247 167
3 Locked QAM256 25 543000000 Hz 10.7 dBmV 40.9 dB 273 170
4 Locked QAM256 26 549000000 Hz 10.5 dBmV 40.7 dB 221 253
5 Locked QAM256 27 555000000 Hz 10.7 dBmV 40.9 dB 205 238
6 Locked QAM256 29 567000000 Hz 10.9 dBmV 40.9 dB 239 259
7 Locked QAM256 30 573000000 Hz 10.6 dBmV 40.8 dB 233 220
8 Locked QAM256 31 579000000 Hz 10.7 dBmV 40.9 dB 261 209
9 Locked QAM256 32 585000000 Hz 10.9 dBmV 41.0 dB 223 253
10 Locked QAM256 33 591000000 Hz 11.1 dBmV 41.1 dB 233 198
11 Locked QAM256 34 597000000 Hz 10.9 dBmV 41.1 dB 198 194
12 Locked QAM256 35 603000000 Hz 10.9 dBmV 41.0 dB 177 254
13 Locked QAM256 36 609000000 Hz 10.9 dBmV 41.1 dB 230 201
14 Locked QAM256 37 615000000 Hz 10.8 dBmV 40.8 dB 182 221
15 Locked QAM256 38 621000000 Hz 10.8 dBmV 40.8 dB 272 247
16 Locked QAM256 39 627000000 Hz 10.9 dBmV 40.7 dB 250 183
17 Locked QAM256 40 633000000 Hz 10.5 dBmV 41.2 dB 0 0
18 Locked QAM256 41 639000000 Hz 10.6 dBmV 41.3 dB 0 0
19 Locked QAM256 42 645000000 Hz 10.6 dBmV 41.4 dB 0 0
20 Locked QAM256 43 651000000 Hz 10.6 dBmV 41.4 dB 0 0
21 Locked QAM256 44 657000000 Hz 10.5 dBmV 41.2 dB 0 0
22 Locked QAM256 45 663000000 Hz 10.6 dBmV 41.0 dB 0 0
23 Locked QAM256 46 669000000 Hz 10.7 dBmV 41.3 dB 0 0
24 Locked QAM256 47 675000000 Hz 10.8 dBmV 40.9 dB 0 0

 

Upstream Bonded Channels

Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 4 5120 Ksym/sec 16500000 Hz 46.3 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 36100000 Hz 44.5 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29600000 Hz 45.3 dBmV
4 Locked ATDMA 3 5120 Ksym/sec 23000000 Hz 45.5 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

 

Current System Time: Thu May 23 19:27:55 2019

System Up Time: 25:03:44

 

Event Log

Time Priority Description
2019-05-23, 19:02:22.0 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-05-23, 19:02:06.0 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.0;CM-VER=3.0;
2019-05-23, 19:01:38.0 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:57:18.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:57:05.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:57:05.0 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:57:05.0 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:56:42.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:56:42.0 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:56:42.0 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:43:19.0 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-05-23, 18:42:50.0 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.0;CM-VER=3.0;
2019-05-23, 18:42:34.0 Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.0;CM-VER=3.0;
2019-05-23, 18:42:11.0 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:37:50.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:37:43.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:37:43.0 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:37:11.0 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:37:10.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:36:38.0 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:21:09.0 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-05-23, 18:20:58.0 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.0;CM-VER=3.0;
2019-05-23, 18:20:26.0 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:16:07.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:15:58.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:15:58.0 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:15:58.0 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:15:19.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:15:19.0 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 18:15:19.0 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:19:54.0 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2019-05-23, 17:19:36.0 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.0;CM-VER=3.0;
2019-05-23, 17:19:14.0 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:14:54.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:14:42.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:14:42.0 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:14:42.0 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:14:18.0 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:14:18.0 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;
2019-05-23, 17:14:18.0 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=cc:40:d0:28:48:90;CMTS-MAC=00:01:5c:9c:00:5a;CM-QOS=1.1;CM-VER=3.0;

 

 

 

Expert

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

Sounds like this is with a WiFi connection ? If so, for a test, does a computer hardwired directly to the router / gateway device with an ethernet cable have the same problem ?



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Regular Visitor

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

We've been having the problem all morning. It just happened again. I connected my laptop to the device with a network cable as you suggested. It had a disconnect at the same time as the wireless devices. When the connection came back, wired and wireless devices were connected again.

 

We have been using the Xfinity app on a mobile phone to check the status when we experience problems. It has been showing the disconnects.

Highlighted
Expert

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

Even though the signal stats looked o/k at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) somewhere.

 

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

 

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They can poll for those upstream stats, check the CMTS (Cable Modem Termination System) for any real time degradation and / or error reports, see your node / cable plant and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem.

 

You should get a reply here in your topic. Good luck !



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Regular Visitor

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

Thanks so much for taking the time to look into it!

Expert

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

Quite welcome ! Smiley Happy



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Contributor

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

I believe your downstream power levels are too high ( yours are over 10) unless there is an amp in the line you will need a tech to diagnose.

Expert

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

10 db is o/k. Even if it weren't they wouldn't need a tech. A self installed 3 dB attenuator would work.



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Contributor

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

According to the posted troubleshooting guides downstream power is a max of 10, the levels are over 10.  Either there is an amplifier or the signal is being delivered by Comcast at that level, the solution is to attenuate, either by removing any amplification or installing an attenuator/splitter. I may be incorrect but, my understanding was that any  problem outside a customers premises would be corrected by Comcast at no charge. My thought would be to let Comcast correct the power level rather than purchasing and installing an attenuator myself.

Expert

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

It a half of a dB over.... And that's only a guide to a recommended level anyway.. The max DOCSIS and manufacturer spec before the modem's front end receiver is saturated is +15 dB. And I did mention a 3 dB attenuator. Preferably a forward path only one so as not to affect the upstream power adversely. The OP is welcome to try one for the halibut.



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Official Employee

Re: Netgear AC1900 C7100V Cable Modem Voice Router - Frequent Disconnects from the Internet

Hey there, 6784014! Thank you for taking the time to reach out to us here on the forums. I'd love to have the opportunity to take a look at this further with you and review the modem and node health. To get started, please send me a PM with your first and last name. Thank you! 

To send me a Private Message, please click my name “ComcastAlly” and click “send a message.”


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