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user_f0afbf
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Thu, Sep 22, 2022 2:55 PM

Internet Dropping Periodically (once or twice a week) or every 30 minutes sometimes

Hello, I have a NETGEAR Nighthawk Cable Modem WiFi Router Combo C7000v2 and running firmware V1.03.08

I have two issues that are happening:

Scenario 1: The internet drops once or twice a week and I have to reboot the Netgear combo router/modem to get it back up. (been happening for more than 6 months)

Scenario 2: Started happening today, internet goes down for 30 minutes and then comes back up and do the same thing over and over.

I rebooted, replaced coaxial cables and splitter and made sure they are plugged in all the way. 

I looked at my router logs and I saw the time is behind by 1 hour from what it should be (Central Time) I also noticed some critical alerts at the same time the internet was dropping and coming back up and I think it has something to do with the issue

Time Priority Description
2022-9-22, 08:17:23 Warning (5) MDD message timeout;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.1;CM-VER=3.0;
1970-1-1, 00:01:09 Notice (6) Honoring MDD; IP provisioning mode = IPv6
1970-1-1, 00:00:45 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:42 Notice (6) WiFi Interface [wl1] set to Channel 153 (Side-Band Channel:N/A) - Reason:INIT
1970-1-1, 00:00:42 Notice (6) WiFi Interface [wl0] set to Channel 6 (Side-Band Channel:10) - Reason:INIT
1970-1-1, 00:00:39 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:14:48 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:34 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:33 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:33 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:26 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:18 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:11 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:10 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:09 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:13:06 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:11:18 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:44 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:38 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:06:38 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:44 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:38 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 08:01:04 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.1;CM-VER=3.0;
2022-9-22, 07:48:17 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:48:15 Critical (3) No UCDs Received - Timeout;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:58 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:57 Critical (3) No UCDs Received - Timeout;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:41 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:39 Critical (3) No UCDs Received - Timeout;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:22 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:21 Critical (3) No UCDs Received - Timeout;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:04 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:47:03 Critical (3) No UCDs Received - Timeout;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:46:46 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:46:45 Critical (3) No UCDs Received - Timeout;;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:46:28 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:46:26 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XX:XX:XX:XX:XX:XX;CM-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:45:36 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:45:08 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=XX:XX:XX:XX:XX:XX;CM-QOS=1.0;CM-VER=3.0;
2022-9-22, 07:45:03 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XX:XX:XX:XX:XX:XX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;

Can someone please he

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11 d ago

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Accepted Solution

EG

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95.9K Messages

12 d ago

Everything is out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels. The connection quality is terrible ! I'm surprised that you are able to be online at all.....

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are there 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 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, 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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user_f0afbf

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@EG​ Thank you SO much for looking into it and for your valuable feedback. I scheduled an Xfinity tech to come in tomorrow and check on it.

I appreciate it  

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12 d ago

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EG

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@user_f0afbf

You're very welcome ! Good luck with it ! Please post back here with how things turn out.

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.

Was your question answered? Please mark an Accepted Answer!tick

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user_f0afbf

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@EG​ 

The tech went up the poll and replaced the splitter that is there which was rated for indoor and not outdoor. He also found 6 splitters on the way to my modem inside the house that are outdated and he got rid of all of them except the one that is before the TV X1 Box and the modem/router. I only have 1 splitter on my main feed inside my house:) YAYYYYYY

The levels are as follows after removing all the splitters:

 
Apply               Cancel     
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 495000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 33 495000000 Hz -1.7 dBmV 38.9 dB 10 0
2 Locked QAM256 42 447000000 Hz -2.5 dBmV 38.1 dB 6 0
3 Locked QAM256 43 453000000 Hz -2.1 dBmV 38.4 dB 6 0
4 Locked QAM256 44 459000000 Hz -2.2 dBmV 38.4 dB 6 0
5 Locked QAM256 45 465000000 Hz -2.2 dBmV 38.3 dB 7 0
6 Locked QAM256 38 471000000 Hz -2.2 dBmV 38.3 dB 8 0
7 Locked QAM256 39 477000000 Hz -1.9 dBmV 38.6 dB 17 0
8 Locked QAM256 40 483000000 Hz -2 dBmV 38.6 dB 11 0
9 Locked QAM256 41 489000000 Hz -1.9 dBmV 38.7 dB 10 0
10 Locked QAM256 34 507000000 Hz -1.8 dBmV 38.2 dB 17 0
11 Locked QAM256 35 513000000 Hz -1.8 dBmV 38.6 dB 17 0
12 Locked QAM256 36 519000000 Hz -1.5 dBmV 38.8 dB 11 0
13 Locked QAM256 1 525000000 Hz -1.6 dBmV 38.6 dB 19 0
14 Locked QAM256 2 531000000 Hz -1.4 dBmV 38.8 dB 19 0
15 Locked QAM256 3 537000000 Hz -1.4 dBmV 38.8 dB 27 0
16 Locked QAM256 4 543000000 Hz -1.5 dBmV 38.6 dB 23 0
17 Locked QAM256 5 549000000 Hz -2.2 dBmV 39 dB 0 0
18 Locked QAM256 6 555000000 Hz -2.1 dBmV 39.1 dB 0 0
19 Locked QAM256 7 561000000 Hz -2 dBmV 39 dB 0 0
20 Locked QAM256 8 567000000 Hz -2 dBmV 39.1 dB 0 0
21 Locked QAM256 9 573000000 Hz -2.1 dBmV 39.1 dB 0 0
22 Locked QAM256 10 579000000 Hz -2.1 dBmV 39.2 dB 0 0
23 Locked QAM256 11 585000000 Hz -2.2 dBmV 39 dB 0 0
24 Locked QAM256 12 591000000 Hz -2.2 dBmV 38.6 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 49.5 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 35600000 Hz 48.3 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29200000 Hz 49.3 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 16400000 Hz 50 dBmV
5 Locked ATDMA 5 2560 Ksym/sec 40400000 Hz 46.8 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
 
Extended Upstream Transmit Power
Enable Extended Upstream Transmit Power
 
Current System Time:Fri Sep 23 19:29:15 2022
System Up Time:00:53:27

 

The internet is faster now, do you think what I have now is acceptable? 

Thank you!

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11 d ago

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EG

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12 d ago

The time is normal. Cable modems don't do DST. It doesn't affect their performance, only the time / date stamps.

That said. Please also copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.

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user_f0afbf

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@EG​ 

Thank you for your response. Here is the rest of the info

OLD INFO BEFORE REMOVING THE SPLITTERS:

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 573000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 9 573000000 Hz -15.3 dBmV 35.6 dB 216 0
2 Locked QAM256 10 579000000 Hz -14 dBmV 36.6 dB 56 0
3 Locked QAM256 11 585000000 Hz -14.8 dBmV 36 dB 87 2
4 Locked QAM256 12 591000000 Hz -16.5 dBmV 35 dB 81 0
5 Locked QAM256 13 597000000 Hz -17.8 dBmV 34.2 dB 95 0
6 Locked QAM256 14 603000000 Hz -17.7 dBmV 34.2 dB 88 0
7 Locked QAM256 15 609000000 Hz -16.4 dBmV 34.9 dB 85 0
8 Locked QAM256 16 615000000 Hz -15.3 dBmV 35.4 dB 97 0
9 Locked QAM256 17 621000000 Hz -14.6 dBmV 36 dB 82 0
10 Locked QAM256 18 627000000 Hz -15.2 dBmV 35.4 dB 68 0
11 Locked QAM256 19 633000000 Hz -17 dBmV 34.7 dB 123 0
12 Locked QAM256 20 639000000 Hz -17.9 dBmV 33.8 dB 132 0
13 Locked QAM256 21 645000000 Hz -16.8 dBmV 33.9 dB 112 0
14 Locked QAM256 22 651000000 Hz -16.3 dBmV 34.7 dB 68 0
15 Locked QAM256 23 657000000 Hz -15.7 dBmV 35.4 dB 95 0
16 Locked QAM256 24 663000000 Hz -15.6 dBmV 35.5 dB 87 0
17 Locked QAM256 25 669000000 Hz -16.5 dBmV 35.6 dB 0 0
18 Locked QAM256 26 675000000 Hz -18.2 dBmV 34.3 dB 0 0
19 Locked QAM256 27 681000000 Hz -18.8 dBmV 33.5 dB 0 0
20 Locked QAM256 28 687000000 Hz -17.3 dBmV 34.2 dB 0 0
21 Locked QAM256 29 693000000 Hz -16.7 dBmV 35.1 dB 0 0
22 Locked QAM256 30 699000000 Hz -16.6 dBmV 35.5 dB 0 0
23 Locked QAM256 31 705000000 Hz -16.9 dBmV 35.2 dB 0 0
24 Locked QAM256 32 711000000 Hz -16.3 dBmV 35.6 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 16400000 Hz 57 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
 
Extended Upstream Transmit Power
Enable Extended Upstream Transmit Power
 
Current System Time:Thu Sep 22 11:14:07 2022

(edited)

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12 d ago

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