Motorola MB8611 Reboots/Restarts Multiple Times a Day - PLEASE HELP!

I had a technician from Comcast visit my home. They stated it was a known issue and that many people in my area (San Jose) have been experiencing this and its mostly due to old wiring. He updated some of the connectors and wires and things appear to be working. Will update once if I dont see any more issues the rest of the day/week.

The tech came, it did get a bit better. Went from rebooting every hour to rebooting once or 2x per day. But its still happening. They said they are going to escalate the issue. No real fix yet :(

I too am having the same problem.  Sometimes it can happen several times a day.  Othertimes it won't happen at all that day.

I put in a service call with Motorola.  When I turned my modem over to look at the model number and such, I noticed that my coax cable had become slightly loose in the process.  The cable modem rebooted as evidenced by seeing the lights go out and come back on and by seeing that the logs had cleared and had only the boot up and acquire signal logs.

Try tightening all of your coax connections with a wrench.  I'm thinking that when there is a disruption of connectivity, no matter how brief, the cable modem is rebooting.  Ideally the modem would simply work to re-acquire the signal, but perhaps there is a bug in this new code that is causing the cable modem to reboot.  If there is a hiccup, you normally won't notice as many network protocols are reasonably forgiving and will recover, but when there is an outage you will know.

(I worked as a network engineer for many years and have solved a few of these maddening problems over the years.  Problems like due to firmware, heat, and bad new parts.  A loose cable like this may not happen in a lab environment where they test the firmware.)

Same here. No improvement after technician visiting, but a promise to escalate.

@user_c5a405  My mb8611 performance is impeccable, so could there possibly be a conflict of some sort between the mb8611 and the router and devices attached to it, there is plenty of documentation of hardware conflicts between different aspects of a network, am curious if it could possibly transfer to the mb8611 possibly being the weakest link… just a thought…

@user_37645  What is interesting is folks on the Cox isp are echoing almost verbatim of what is being of concern here, same modem the mb8611, to me that’s very odd, also with some oddities if I boot into Linux they magically vanish, I wonder if a mb8611 was rebooted with nothing attached to it if would reboot or not…

@user_37645  Cox is fiber, same problem, they actually use the Xb8 as their rented modem, anyway point is I do things differently, settings etc, so as long as someone has devices attached to the mb8611, I don’t see how you could rule out a interaction, reboot nothing attached, that to me would rule out any interaction if it still reboots, if it don’t reboot that’s another story, btw I am not a engineer, but I did stay in a Holiday Inn Express…

@user_c5a405  This is going to probably be confusing, win 10 along with your network card, I am talking basically WiFi but can be complicated, so approximately every 5 - 10  minutes it will disconnect you to search for a better channel, access point, it’s supposed to be seem less, for the majority of people it is, but it sometimes don’t reconnect in a timely fashion, a lot of possibly reasons, it sometimes can take many minutes, so your monitoring software noticed a disconnect, probably possibly what I am describing, so your team call or zoom etc, buffers the call etc, probably different times relative to the software, for me on YouTube, I can pull the plug on my modem, yet the music stream for it seems like minute, I never actually timed it, so after the buffer time it probably disconnects, but it might not actually disconnect but seem to freeze, it was hard for me to diagnose at first for two reasons, first when it happened, it happened like a minute or so before my YouTube etc disconnected, so it was hard to pinpoint, second in the logs I really didn’t see much because it probably wasn’t technically a error if it didn’t loose connection, at this point I am sure you don’t believe me, but this is all verifiable if you search for it.

one thing I always do is in the device manger in win 10, I always uncheck the ‘power management’ box’s on both network cards, even on the Microsoft website they say if you have unexplainable gremlins going on uncheck the box, think about it, I don’t want Microsoft/network card possibly sending less power to my network card etc, possibly throttling me, to save energy, who knows what actually goes on, again this is all verifiable on the web 

Another thing I do is on my router is pick a appropriate channel and bandwidth, I would go lower bandwidth to possibly help if you have a close neighbor to avoid possible overlap of WiFi signals, anyway I take the channel selection off ‘auto’ , another thing I read is to use wpa3 encryption method, supposedly it’s supported to remedy some on this, another thing I did was to refresh my win 10 operating system, after all my computer was over 10 years old, plus I read where wifi6e might have some difficulties some outdated and current build, why I was on the Microsoft download page, I got the expected error that my computer wasn’t capable with win 11, ironically on the Microsoft website it explained how to bypass the errors and install it anyway which I did, sorry I got sidetracked, I did both right into the modem, plus into the router, Linux is on the same computer..

I also have a MB8611 and have noticed this problem the past few days. Seems much worse during work hours, but have noticed it during all hours. I usually have ping plotter going and my connection is solid until it will just randomly reboot every few hours.

I noticed this issue a few times when I signed up for XFinity at the end of December but it went away after a couple days (When there was an acknowledged outage in my area for the good chunk of the day) I assumed it was XFinity sending updates to the modem at this time as part of provisioning. At the time I noticed I was on Software Version 8611-19.2.18 on December 23rd.

Modem is currently on Software Version 8611-21.3.7 . Sadly I did not take note of updates between now and then to see if this "new" version coincided with the these sudden reboots.

@EG  but does have it listed, along with the Xb8 list as a fiber gateway, confusing to me,

https://www.cox.com/residential/support/cox-certified-cable-modems.html 

@emattheis thanks you answered my question about if anything was attached to the modem and it still reboots…

@emattheis  I was just trying to find a common denominator perhaps, throw some ideas, information back and forth, mine don’t reboot, so something’s probably different, but could probably even compare the date of manufacture, anyway I am out

@emattheis My event logs are close when i first boot up, all these critical errors etc, ill post them when i edit them, so i am curious if anyone did a factory reset, plus i was reading that if you unplug the modem for roughly 30 seconds, it will re download the firmware etc, so what if the firmware folks got is semi corrupted, if it reboots and still is using the corrupted firmware, i would expect it to keep being funky, but fresh who knows.. just a thought...

@emattheis Sorry it got marked private, I have edit more

@emattheis sorry its very sloppy, i rebooted my modem earlier, i am working on just using the router portion of a xb8, by passing the modem...