Cable Modem Shut Down

[kenk3664]

After almost 3 years of flawless service, my CM2050V Cable Modem suddenly shut down in the middle of an important online meeting. The modem is well shielded and there were no apparent issues at the time. After checking everything else, I did a reset on the back of the modem, and it started working well again. Here's my question: Should I be worried that this will happen again? Investing in a new modem is not feasible for me right now, and I can't afford to have a backup just in case. Since I haven't experienced this before, I'd appreciate some input.

[FURRYe38]

Lets check a couple of things. 

Modem well cooled in a good ventilated room? 

Please post a copy and paste of the modems connection status and event log page.
https://kb.netgear.com/30007/How-do-I-obtain-the-cable-connection-information-from-a-NETGEAR-cable-m...
https://kb.netgear.com/30008/How-do-I-view-or-clear-the-event-logs-on-my-NETGEAR-cable-modem-or-mode...

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 
What is the brand and model of the host wifi router connected to the modem?

[kenk3664]

I'm sorry.  I have been working on this for quite some time and can't get the files into a format that I can attach here.

[FURRYe38]

Put the data in a word or text file then save off as a PDF then attach to your next post. 

[kenk3664]

The file was too wide and I could not get it into a narrower format.

[FURRYe38]

What values do you see on the cable connections page under Correctables and Un-correctables. They should be mostly zeros here.

Power levels look good.

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.
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-Mod...
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
https://highspeed.tips/docsis-events/

[kenk3664]

The ISP is Comcast.  According to them, anything but their expensive rental unit is the cause of all existing problems in the universe.  There is only one coax entering the house which has one of their splitters on it, one side to Video and one to Internet.  Any signal amplifiers are in the distribution modules, after the modem.  It has been working fine for almost 3 years.  I ran all of the lines in the house using quad-shielded RG6 and Cat 6.  Everything terminates in an On-Q cabinet and their modules.  It's in the basement which is cool to cold.  There are no stress bends or moisture issues.  I suspect that Comcast, or some contractor, just disrupted service and caused the problem.  My concern is, was the problem caused by a problem with the modem such that I might expect it to fail again?  Thanks for your help.  I'll review the error code definitions.

[FURRYe38]

You'll need to ask them to send a tech on site. If the modem had been working up to a certain point then all of a sudden you saw this, and from the Event logs, they need to check there line up to the modem. 

[kenk3664]

There were three similar critical events a few seconds apart preceding the modem shutdown:  Each time it started with a level 6 event, went to a level 5 event and then the level 3 critical event:

"SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=08:36:c9:3c:59:58;CMTS-MAC=00:01:5c:6d:d4:65;CM-QOS=1.1;CM-VER=3.1;"

The explanation of these SYNC timing Synchronization failures says:

"The modem is completely out of service and is unable to hear the ‘sync timing’ pulses on the cable line which occur every 20ms."

This is above my pay grade.  This looks like something caused by the ISP.  If so I'm going to keep the log and not spend a 3 hour window waiting for them to come to my house and say "No Trouble Found." Rather, I'll wait and see if it happens again.  Or is this potentially an internal problem with the modem?

[FURRYe38]

ISP needs to look into this first.