Question Periodic Drops in Internet Connection

TheBigFunk

Distinguished
Sep 23, 2012
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Router: Netgear Nighthawk r7000
Modem: Motorola 24x8, Model MB7621
ISP/Connection Type: Xfinity broadband (175mbps).
Devices Connected: We have 12 items in total connected to our router. 3 on the 2.4GHz . 7 on 5GHz. And 2 that are wired. I've attempted to plug directly into the router with the same issue. 5 computers are connected to our router. (2 work, 3 personal).

Anytime the internet goes down, we remain connected to our Wifi/Router, but receive a 'Connection Refused' message when we try to navigate the web. Our work laptops, which connect to our router/modem, but use a VPN, have been completely unaffected during these periodic drops.

I don't have any switches, and have swapped out the Coaxial cable, plugged directly into the Modem, and still receive the same issue. The times that it drops are seemingly random throughout the day, and can be for under a minute, or up to 30 minutes. Looking at the Error log on our Router I'm seeing a lot of T3 and T4 Errors. Posted the log below. I've checked - and our router also has the most recent Firmware installed.

I've been talking to Xfinity customer service, but they keep pushing their rentable router as a potential solution, and there is a tech coming out this upcoming weekend - but I just want to know, what would cause these issues?

Error Log:
TimePriorityDescription
Wed Apr 21 12:50:53 2021 Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 22 00:57:11 2021 Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Thu Apr 22 00:57:21 2021 Critical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Wed May 26 00:19:46 2021 Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 16 06:44:47 2021 Critical (3)Resetting the cable modem due to docsDevResetNow
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Wed Jun 16 06:44:13 2021 Critical (3)Resetting the cable modem due to docsDevResetNow
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Fri Jun 18 17:51:18 2021 Critical (3)Resetting the cable modem due to docsDevResetNow
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Sat Jun 19 09:53:38 2021 Critical (3)Resetting the cable modem due to docsDevResetNow
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Sun Jun 20 13:09:33 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:10:34 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:10:34 2021 Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:10:55 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:10:55 2021 Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:11:15 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:11:15 2021 Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:11:35 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:11:35 2021 Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:11:55 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:11:55 2021 Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Sun Jun 20 13:11:57 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Sun Jun 20 13:14:44 2021 Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Tue Jun 22 19:23:27 2021 Critical (3)Resetting the cable modem due to docsDevResetNow
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Wed Jun 23 02:12:12 2021 Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.1;CM-VER=3.0;
Wed Jun 23 18:08:31 2021 Critical (3)Resetting the cable modem due to docsDevResetNow
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=00:40:36:70:e1:99;CMTS-MAC=00🇨🇨fc:60:37:21;CM-QOS=1.0;CM-VER=3.0;
Time Not EstablishedNotice (6)Honoring MDD; IP provisioning mode = IPv6

Downstream Bonded Channels:
[TD] Channel[/TD]
[TD]Lock Status[/TD]
[TD]Modulation[/TD]
[TD]Channel ID[/TD]
[TD]Freq. (MHz)[/TD]
[TD]Pwr (dBmV)[/TD]
[TD]SNR (dB)[/TD]
[TD]Corrected[/TD]
[TD]Uncorrected[/TD]​
[TD]1[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]17[/TD]
[TD]525.0[/TD]
[TD]2.5[/TD]
[TD]36.9[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]2[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]21[/TD]
[TD]549.0[/TD]
[TD]3.0[/TD]
[TD]37.0[/TD]
[TD]2[/TD]
[TD]0[/TD]​
[TD]3[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]22[/TD]
[TD]555.0[/TD]
[TD]3.0[/TD]
[TD]37.0[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]4[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]23[/TD]
[TD]561.0[/TD]
[TD]3.2[/TD]
[TD]37.0[/TD]
[TD]3[/TD]
[TD]0[/TD]​
[TD]5[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]24[/TD]
[TD]567.0[/TD]
[TD]3.4[/TD]
[TD]37.0[/TD]
[TD]5[/TD]
[TD]0[/TD]​
[TD]6[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]1[/TD]
[TD]411.0[/TD]
[TD]0.1[/TD]
[TD]36.9[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]7[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]2[/TD]
[TD]417.0[/TD]
[TD]0.3[/TD]
[TD]36.9[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]8[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]3[/TD]
[TD]423.0[/TD]
[TD]0.6[/TD]
[TD]37.0[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]9[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]4[/TD]
[TD]435.0[/TD]
[TD]1.4[/TD]
[TD]37.1[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]10[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]5[/TD]
[TD]447.0[/TD]
[TD]1.6[/TD]
[TD]37.1[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]11[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]6[/TD]
[TD]453.0[/TD]
[TD]1.6[/TD]
[TD]37.1[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]12[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]7[/TD]
[TD]459.0[/TD]
[TD]1.6[/TD]
[TD]37.0[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]13[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]8[/TD]
[TD]465.0[/TD]
[TD]1.8[/TD]
[TD]37.1[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]14[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]9[/TD]
[TD]471.0[/TD]
[TD]2.1[/TD]
[TD]37.2[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]15[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]10[/TD]
[TD]477.0[/TD]
[TD]2.0[/TD]
[TD]37.2[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]16[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]11[/TD]
[TD]483.0[/TD]
[TD]1.9[/TD]
[TD]37.2[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]17[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]12[/TD]
[TD]489.0[/TD]
[TD]1.7[/TD]
[TD]37.8[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]18[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]13[/TD]
[TD]495.0[/TD]
[TD]1.7[/TD]
[TD]37.6[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]19[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]14[/TD]
[TD]507.0[/TD]
[TD]2.0[/TD]
[TD]37.7[/TD]
[TD]1[/TD]
[TD]0[/TD]​
[TD]20[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]15[/TD]
[TD]513.0[/TD]
[TD]1.9[/TD]
[TD]37.7[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]21[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]16[/TD]
[TD]519.0[/TD]
[TD]1.8[/TD]
[TD]36.8[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]22[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]18[/TD]
[TD]531.0[/TD]
[TD]2.4[/TD]
[TD]36.8[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]23[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]19[/TD]
[TD]537.0[/TD]
[TD]2.6[/TD]
[TD]35.2[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]24[/TD]
[TD]Locked[/TD]
[TD]QAM256[/TD]
[TD]20[/TD]
[TD]543.0[/TD]
[TD]2.5[/TD]
[TD]36.7[/TD]
[TD]0[/TD]
[TD]0[/TD]​
[TD]Total[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]11[/TD]
[TD]0[/TD]​



Upstream Bonded Channels:
[TD] Channel[/TD]
[TD]Lock Status[/TD]
[TD]Channel Type[/TD]
[TD]Channel ID[/TD]
[TD]Symb. Rate (Ksym/sec)[/TD]
[TD]Freq. (MHz)[/TD]
[TD]Pwr (dBmV)[/TD]​
[TD]1[/TD]
[TD]Locked[/TD]
[TD]ATDMA[/TD]
[TD]5[/TD]
[TD]2560[/TD]
[TD]40.4[/TD]
[TD]42.5[/TD]​
[TD]2[/TD]
[TD]Locked[/TD]
[TD]ATDMA[/TD]
[TD]1[/TD]
[TD]5120[/TD]
[TD]16.4[/TD]
[TD]45.4[/TD]​
[TD]3[/TD]
[TD]Locked[/TD]
[TD]ATDMA[/TD]
[TD]2[/TD]
[TD]5120[/TD]
[TD]22.8[/TD]
[TD]45.0[/TD]​
[TD]4[/TD]
[TD]Locked[/TD]
[TD]ATDMA[/TD]
[TD]3[/TD]
[TD]5120[/TD]
[TD]29.2[/TD]
[TD]44.3[/TD]​
[TD]5[/TD]
[TD]Locked[/TD]
[TD]ATDMA[/TD]
[TD]4[/TD]
[TD]5120[/TD]
[TD]35.6[/TD]
[TD]43.9[/TD]​
[TD]6[/TD]
[TD]Not Locked[/TD]
[TD]Unknown[/TD]
[TD]0[/TD]
[TD]0[/TD]
[TD]0[/TD]
[TD]0.0[/TD]​
[TD]7[/TD]
[TD]Not Locked[/TD]
[TD]Unknown[/TD]
[TD]0[/TD]
[TD]0[/TD]
[TD]0[/TD]
[TD]0.0[/TD]​
[TD]8[/TD]
[TD]Not Locked[/TD]
[TD]Unknown[/TD]
[TD]0[/TD]
[TD]0[/TD]
[TD]0[/TD]
[TD]0.0[/TD]​



Thank you!
 
That sure did not cut and paste well. Check the values with one of sites that has the recommended signals levels. It varies a bit based on the encoding. I think it is ok but it is extremely hard to tell.

SYNC errors are almost always the ISP equipment problem. The reset message is the ISP equipment telling your modem to reboot/train.

My guess is this is not a problem with your modem but it might be.

Call the ISP they can see these messages and they should also be able to see messages from their equipment that may tell more about why for example it sends you a reset.
 
Reactions: TheBigFunk

TheBigFunk

Distinguished
Sep 23, 2012
11
0
18,510
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That sure did not cut and paste well. Check the values with one of sites that has the recommended signals levels. It varies a bit based on the encoding. I think it is ok but it is extremely hard to tell.

SYNC errors are almost always the ISP equipment problem. The reset message is the ISP equipment telling your modem to reboot/train.

My guess is this is not a problem with your modem but it might be.

Call the ISP they can see these messages and they should also be able to see messages from their equipment that may tell more about why for example it sends you a reset.
v


Oh boy - sorry about that, didn't catch that those didn't paste over well.

I'll check the recommended signal levels.


Here's the Downstream:
Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
1 Locked QAM256 17 525.0 2.5 37.3 1 0
2 Locked QAM256 21 549.0 2.9 37.4 4 0
3 Locked QAM256 22 555.0 3.0 37.4 2 0
4 Locked QAM256 23 561.0 3.2 37.4 4 0
5 Locked QAM256 24 567.0 3.4 37.4 6 0
6 Locked QAM256 1 411.0 -0.2 37.2 0 0
7 Locked QAM256 2 417.0 0.0 37.3 0 0
8 Locked QAM256 3 423.0 0.5 37.5 0 0
9 Locked QAM256 4 435.0 1.4 37.7 0 0
10 Locked QAM256 5 447.0 1.6 37.6 0 0
11 Locked QAM256 6 453.0 1.5 37.6 0 0
12 Locked QAM256 7 459.0 1.6 37.6 0 0
13 Locked QAM256 8 465.0 1.8 37.6 0 0
14 Locked QAM256 9 471.0 2.1 37.7 0 0
15 Locked QAM256 10 477.0 2.1 37.7 0 0
16 Locked QAM256 11 483.0 2.0 37.7 0 0
17 Locked QAM256 12 489.0 1.8 38.3 0 0
18 Locked QAM256 13 495.0 1.8 38.2 0 0
19 Locked QAM256 14 507.0 2.1 38.3 1 0
20 Locked QAM256 15 513.0 2.1 38.1 0 0
21 Locked QAM256 16 519.0 1.9 37.2 0 0
22 Locked QAM256 18 531.0 2.4 37.1 0 0
23 Locked QAM256 19 537.0 2.7 36.2 0 0
24 Locked QAM256 20 543.0 2.6 37.3 1 0
Total 19 0


Upstream:
Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
1 Locked ATDMA 5 2560 40.4 42.5
2 Locked ATDMA 1 5120 16.4 45.4
3 Locked ATDMA 2 5120 22.8 45.0
4 Locked ATDMA 3 5120 29.2 44.3
5 Locked ATDMA 4 5120 35.6 43.9
6 Not Locked Unknown 0 0 0 0.0
7 Not Locked Unknown 0 0 0 0.0
8 Not Locked Unknown 0 0 0 0.0
 

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