Internet constantly losing connection - Multiple Errors Reported by my Netgear CM1000v2 Cable Modem

[band_of_gypsys]

Xfinity Internet - 500Mbps Download Package

Netgear - CM1000v2 - Cable Modem - (Firmware v10.01.07)

Internet has been fine for over 4 years, last week connection started to drop out every 2 hours or so. Now it's dropping every 5-10 minutes.

I only use wi-fi for phone etc, everything else is wired. I lose both LAN and wi-fi.

No splitters, all new cables. I first thought it might be the router (Netgear xr300) so I plugged my computer directly into the modem. Did not solve the issue.

Logs and Connection Stats are as follows:

Time Priority Description 2024-05-12, 20:09:23 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out; 2024-05-12, 20:08:55 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3. 2024-05-12, 20:08:08 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out; 2024-05-12, 19:39:31 Critical (3) UCD invalid or channel unusable; 2024-05-12, 19:39:31 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.; 2024-05-12, 19:39:20 Notice (6) Honoring MDD; IP provisioning mode = IPv6 2024-05-12, 19:39:15 Critical (3) UCD invalid or channel unusable; 2024-05-12, 19:38:55 Notice (6) Honoring MDD; IP provisioning mode = IPv6 2024-05-12, 19:38:41 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out; 2024-05-12, 19:30:37 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out; 2024-05-12, 19:29:37 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.; 2024-05-12, 19:19:24 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out 2024-05-12, 19:18:41 Warning (5) Dynamic Range Window violation 2024-05-12, 19:18:41 Warning (5) RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW; 2024-05-12, 19:14:29 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out; 2024-05-12, 19:10:21 Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.; 2024-05-12, 19:06:03 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out; 2024-05-12, 19:06:03 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.; 2024-05-12, 19:06:03 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out; 2024-05-12, 19:03:07 Critical (3) UCD invalid or channel unusable; 2024-05-12, 19:03:07 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.; 2024-05-12, 19:02:57 Notice (6) Honoring MDD; IP provisioning mode = IPv6 2024-05-12, 19:02:52 Critical (3) UCD invalid or channel unusable; 2024-05-12, 19:02:30 Notice (6) Honoring MDD; IP provisioning mode = IPv6 2024-05-12, 19:02:19 Critical (3) SYNC Timing Synchronization failure - Loss of Sync; 2024-05-12, 19:01:44 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing; 2024-05-12, 19:01:38 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out; 2024-05-12, 19:01:38 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing; 2024-05-12, 19:01:37 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out; 2024-05-12, 19:00:57 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing; 2024-05-12, 19:00:54 Warning (5) MDD message timeout; 2024-05-12, 19:00:49 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing; 2024-05-12, 19:00:45 Warning (5) MDD message timeout; 2024-05-12, 19:00:45 Notice (6) CM-STATUS message sent. Event Type Code: 2; Chan ID: 24 26; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.; 2024-05-12, 18:51:56 Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.; 2024-05-12, 18:48:58 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.; 2024-05-12, 18:47:03 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out; 2024-05-12, 18:40:16 Warning (5) Dynamic Range Window violation 2024-05-12, 18:40:16 Warning (5) RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW; 2024-05-12, 18:39:44 Critical (3) UCD invalid or channel unusable;

Startup Procedure

Procedure Status Comment Acquire Downstream Channel 711000000 Hz Locked Connectivity State OK Operational Boot State OK Operational Security Enable BPI+ IP Provisioning Mode Honor MDD IPv6 only

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Frequency Power SNR / MER Unerrored Codewords Correctable Codewords Uncorrectable Codewords 1 Locked QAM256 44 711000000 Hz 12.3 dBmV 43.9 dB 206325110 784 2361 2 Locked QAM256 13 525000000 Hz 12.3 dBmV 44.4 dB 203460722 4958 8837 3 Locked QAM256 14 531000000 Hz 12.0 dBmV 44.3 dB 213547814 13059 9223 4 Locked QAM256 15 537000000 Hz 11.8 dBmV 44.1 dB 203411821 12639 14272 5 Locked QAM256 16 543000000 Hz 11.9 dBmV 44.4 dB 213606604 13666 8413 6 Locked QAM256 17 549000000 Hz 12.3 dBmV 44.5 dB 203461579 6788 11153 7 Locked QAM256 18 555000000 Hz 12.1 dBmV 44.3 dB 213613852 8335 13884 8 Locked QAM256 19 561000000 Hz 12.0 dBmV 44.2 dB 203502668 4053 8409 9 Locked QAM256 20 567000000 Hz 12.2 dBmV 44.3 dB 203336530 1124 3219 10 Locked QAM256 21 573000000 Hz 12.5 dBmV 44.6 dB 203348812 6781 23883 11 Locked QAM256 22 579000000 Hz 12.4 dBmV 44.4 dB 203356492 732 1760 12 Locked QAM256 23 585000000 Hz 11.9 dBmV 44.1 dB 203518138 8570 14595 13 Locked QAM256 24 591000000 Hz 12.0 dBmV 44.0 dB 203376584 812 2573 14 Locked QAM256 25 597000000 Hz 12.6 dBmV 44.4 dB 203451738 22198 33752 15 Locked QAM256 26 603000000 Hz 12.6 dBmV 44.4 dB 203395042 838 2305 16 Locked QAM256 27 609000000 Hz 12.0 dBmV 44.0 dB 213566160 26475 34354 17 Locked QAM256 28 615000000 Hz 11.8 dBmV 43.9 dB 213711803 8841 7837 18 Locked QAM256 29 621000000 Hz 12.4 dBmV 44.2 dB 213701708 9835 21587 19 Locked QAM256 30 627000000 Hz 12.5 dBmV 44.4 dB 203571765 8332 19209 20 Locked QAM256 31 633000000 Hz 12.0 dBmV 44.1 dB 213740586 6210 7879 21 Locked QAM256 32 639000000 Hz 11.8 dBmV 43.9 dB 203635059 3871 3688 22 Locked QAM256 33 645000000 Hz 12.0 dBmV 44.1 dB 213764673 3994 8665 23 Locked QAM256 34 651000000 Hz 12.3 dBmV 44.4 dB 203641582 3725 8396 24 Locked QAM256 35 657000000 Hz 11.8 dBmV 44.2 dB 213778657 5145 7024 25 Locked QAM256 36 663000000 Hz 11.2 dBmV 43.7 dB 203656039 3175 7285 26 Locked QAM256 37 669000000 Hz 11.2 dBmV 44.0 dB 213802742 3192 4992 27 Locked QAM256 38 675000000 Hz 11.9 dBmV 44.1 dB 203673324 6119 7038 28 Locked QAM256 39 681000000 Hz 11.8 dBmV 44.2 dB 213820996 4132 4950 29 Locked QAM256 40 687000000 Hz 11.2 dBmV 43.8 dB 203697972 3387 6287 30 Locked QAM256 41 693000000 Hz 11.0 dBmV 43.5 dB 203723180 6760 5507 31 Locked QAM256 42 699000000 Hz 11.5 dBmV 43.8 dB 203739937 4464 6159 32 Locked QAM256 43 705000000 Hz 11.8 dBmV 44.1 dB 203758486 3604 3564

Upstream Bonded Channels Channel Lock Status Modulation Channel ID Frequency Power 1 Locked ATDMA 17 16400000 Hz 48.3 dBmV 2 Locked ATDMA 18 22800000 Hz 45.3 dBmV 3 Locked ATDMA 19 29200000 Hz 47.8 dBmV 4 Locked ATDMA 20 35600000 Hz 48.5 dBmV 5 Not Locked Unknown 0 0 Hz 0.0 dBmV 6 Not Locked Unknown 0 0 Hz 0.0 dBmV 7 Not Locked Unknown 0 0 Hz 0.0 dBmV 8 Not Locked Unknown 0 0 Hz 0.0 dBmV Downstream OFDM Channels Channel Lock Status Modulation / Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier Number Range Unerrored Codewords Correctable Codewords Uncorrectable Codewords 1 Locked 0, 1, 2, 3 193 957000000 Hz 14.6 dBmV 43.8 dB 148 ~ 3947 51507466 605168 17578 2 Not Locked 0 0 0 Hz 7.9 dBmV 0.0 dB 0 ~ 4095 0 0 0 Upstream OFDMA Channels Channel Lock Status Modulation / Profile ID Channel ID Frequency Power 1 Not Locked Unknown 0 0 Hz 0 dBmV 2 Not Locked Unknown 0 0 Hz 0 dBmV

[FURRYe38]

Power levels are too high:

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

I'd get a -6dbm cable coax line attenuator installed. 

You have tons of correctables and un-correctables that is supposed to be zeros. 

Any Criticals, Errors or Warnings seen in the event logs needs to be reviewed and resolved by the ISP. Indicates a signal issue on the ISP line up to the modem.

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
https://highspeed.tips/docsis-events/

[band_of_gypsys]

Yeah, good luck getting in contact with someone from Xfinity lol!

They make it impossible to actually get a tech or even customer service on the phone.

Thanks for the reply! :))

[FURRYe38]

Never have been a fan of that ISP. 

Good Luck.