CM400 keeps dropping internet

Question

My configuration is a CM400 modem with a TP-Link router. For a past few days it keeps dropping internet. To rule out TP-Link router issues, I tried to swap out my router with a older one but it does not help. Contacted XFinity and after running their tests they say things are fine from their end.
I tried to login to the modem and check the event logs. I see this the below. Please help how to fix this issue.
Firmware Version

V2.01.06

Startup Procedure

Procedure	Status	Comment
Acquire Downstream Channel	447000000 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	QAM 256	4	405000000 Hz	9.7 dBmV	34.7 dB	13543	88504
2	Locked	QAM 256	5	411000000 Hz	9.3 dBmV	36.3 dB	44963	110851
3	Locked	QAM 256	6	417000000 Hz	9.6 dBmV	36.6 dB	45948	108370
4	Locked	QAM 256	7	423000000 Hz	9.6 dBmV	37.0 dB	48843	147507
5	Locked	QAM 256	8	429000000 Hz	9.5 dBmV	37.6 dB	44307	135525
6	Locked	QAM 256	9	435000000 Hz	10.1 dBmV	37.6 dB	44535	140135
7	Locked	QAM 256	10	441000000 Hz	9.6 dBmV	37.3 dB	50812	179820
8	Locked	QAM 256	11	447000000 Hz	9.4 dBmV	37.0 dB	45357	110663

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	7	5120 Ksym/sec	16400000 Hz	46.3 dBmV
2	Locked	ATDMA	8	5120 Ksym/sec	22800000 Hz	46.5 dBmV
3	Locked	ATDMA	9	5120 Ksym/sec	29200000 Hz	47.0 dBmV
4	Locked	ATDMA	10	5120 Ksym/sec	35600000 Hz	48.0 dBmV

Current System Time: Wed Feb 16 18:45:18 2022

System Up Time: 04:45:55

and the event log says -

Time	Priority	Description
Feb 16 10:02:39 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:02:48 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:04:18 2022	Critical (3)	No Ranging Response received - T3 time-out
Feb 16 10:04:23 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:07:45 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:07:53 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:08:03 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:08:04 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:08:04 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:08:29 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:08:44 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:09:28 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:09:48 2022	Critical (3)	No Ranging Response received - T3 time-out
Feb 16 10:09:53 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:10:10 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:10:12 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:12:58 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:13:02 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:13:07 2022	Critical (3)	No Ranging Response received - T3 time-out
Feb 16 10:13:13 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:13:15 2022	Critical (3)	No Ranging Response received - T3 time-out
Feb 16 10:13:34 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:13:56 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:14:11 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:14:25 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:14:35 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:17:22 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 10:17:28 2022	Warning (5)	Lost MDD Timeout
Feb 16 10:21:13 2022	Warning (5)	MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Feb 16 12:55:02 2022	Warning (5)	Lost MDD Timeout
Feb 16 13:50:57 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync
Feb 16 13:51:01 2022	Warning (5)	Lost MDD Timeout
Feb 16 13:53:12 2022	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out
Feb 16 13:53:19 2022	Warning (5)	Lost MDD Timeout
Feb 16 13:53:49 2022	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out
Feb 16 13:55:08 2022	Warning (5)	MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out
Feb 16 13:59:58 2022	Warning (5)	MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Feb 16 14:05:27 2022	Warning (5)	Lost MDD Timeout
Feb 16 14:05:35 2022	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync

FURRYe38 · Answer

&nbsp;
You have correct and un-correctables which should be near zero.
Power levels are a bit too high:
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router?article=24311
&nbsp;
Have the ISP check the signal and line quality UP to the modem.&nbsp;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.&nbsp;Be sure your using good quality RG6 coax cable up to the modem.&nbsp;Be sure to power OFF the modem for 1 minute then back ON.https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Modems/m-p/1530376#M12853
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
&nbsp;

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CM400 keeps dropping internet

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