Motorola MB8611 modem keeps restarting - firmware issue

FWIW - I have 4 upstream channels and have the reboot issue. My upstream channels do show as type SC-QAM. My upstream Pwr (dBmV) is 49ish which seems to be a little over spec.

@user_210e12  Just curious if the symb rate is all the same for all four upstream channels?

Same modem an issue where my modem is rebooting itself several times a day with the current firmware - 8611-21.3.7

I had exactly the same problem since later Dec 2022.  current firmware version 8611-21.3.7.   It has rebooted 5 times over the past 7 hours.

Still no fix?   Why doesn't xfinity just revert to the older firmware that doesn't break?  

Anyone switching to AT&T Fiber?  This is just embarrassing for them.

My modem rebooted and picked up 8611-19.2.18 which appears to be working fine. I hope they don't try to push the bad update to my modem again. xFinity, please fix your software pushes.

Just wanted to add in and say I experienced the worst week of headaches from troubleshooting this stupid modem. Motorola and Xfinity need to figure this out, or at least acknowledge the issue and let potential customers know there is a current issue with the MB8611 and xfinity. We shouldn't have to be doing their job, for free!! I finally gave up and reverted to my older Motorola MB7220 and haven't had a single disconnect yet.

Just adding my experience to the list here. I upgraded to an MB8611 back in September 2022 and had zero issues until late December 2022. My modem shows the same behavior as others... rebooting randomly and bouncing between the two different versions of firmware.

Xfinity support wasn't very helpful. I eventually insisted they send a tech out. The tech was only somewhat more helpful... they confirmed that my modem had rebooted 84 times in last month. They checked all of my connections (both inside and outside) and my signal levels were in spec. I lost faith when they kept insisting that I had to upgrade my modem's firmware to resolve the problem. (The DOCSIS standard doesn't permit that.)

I've tried re-activating my modem, but that didn't help. (Mentioned as a possible fix on a Reddit thread.)

I've started the RMA process with Motorola Network, but they are dragging their feet. (Maybe they know something is up?)

I only upgraded to this modem because I wanted something that was supported and provided 2.5GbE for future proofing. I thought, maybe I'll just get an Arris S33 and see if that fairs better... but it looks like folks are reporting similar issues with that device. Here's hoping this mess gets sorted out.

If only I hadn't sold my old Netgear CM1000!

I've had an open ticket with Motorola regarding this issue. According to the tech, Motorola/Comcast pushed out a "fixed" version of the firmware last week. I re-activated my MB8611 and did a factory reset, and my modem is now running 19.2.18 as well. I haven't had a reboot in the last 24 hours.

Is 19.2.18 a previous firmware? Why would a newer version be a lower number?

Can also confirm. I lost DS lock (flashing blue DS light) last week and rebooted this morning. Modem would not lock DS or US and rebooted again on its own. After 2nd reboot, both DS & US finally locked. Logged in to modem and found it had downgraded to 19.2.18. I'm now able to ping the modem, which seemed to be disabled with the last firmware update.

Just a note, I've been running 21.3.7 without any issues on the MB8611. After the update on Jan. 02, the signals were better than it has ever been and performance was stable until I lost DS lock last week. I may be one of the luckier ones with the new firmware.

I have been reading this thread for a few weeks as my MB8611 I bought in October 2022 started randomly rebooting since mid-December. Although not as bad as others, I decided to RMA it with Motorola. I got the replacement today (Feb 7), activated it and it literally rebooted 10 times in 3 hours! It is like Internet freezes, all lights freeze on modem then hard restarts. I ended up pulling out my old Netgear CM600 and have been fine since reactivating that one. I'll let the MB8611 sit for a couple weeks and retry activating and see if things change. BTW, it came with firmware 19.2.18 and never upgrade or downgraded during any reboots that I could tell. No real story in event logs and all my specs are within range with zero uncorrected errors. 

Like most people I've been having the issue with the MB8611 and have contacted both Xfinity and Motorola about it. At this moment I am using the Xfinity Gateway because I refuse to buy another $200 modem and I got Xfinity to cave on giving me $32 of credit to cover two months for the gateway. After being on the phone with Xfinity for 2 hours, the agent I spoke to stated that they have updated the service on their end and that any further issues stem from the modem. 

I'm currently holding Motorola hostage by refusing to send them the tracking number for the RMA return because they refuse to respond otherwise.

Email 1 - "The ISP is aware of the issue and is pushing firmware updates out regionally across their network to resolve the issue. The update should hopefully reach your region within a timely manner. That is all the information we have been provided by Comcast."

Email 2 - "The replacement unit is a tested 100% fully functional device. The update may have not reached your region yet as they are updating devices regionally so the local technicians may not be informed of the updates yet.  That is unfortunately completely out of Motorola's hands."

Email 3 - "the firmware on the unit has to match what is approved in your area. Even if we put the up to date firmware on the unit the ISP would just overwrite it automatically the moment it connects to their coaxial line. If the update has not reached your area then that would have occurred. At this moment there is nothing more that we are able to do for the issue. It is in Comcast's hands with how they update the devices and what regions get the updates first. We cannot be of any more assistance in that regard. "

Email 4 - "The update is not just firmware, I have mentioned the update several times but at no point did I state it was just a firmware change. The update is several things including changes on their networks back end. I cannot say anymore in regards to the changes they are making sir as it is outside of our ability to speak on.  The firmware itself is going to be 8611-19.2.18, however there is a chance that you have been put on that firmware and they just havent made whatever changes they need to make on the back end. I cannot say for certain as Comcast does not provide that level of information to outside sources. We as a company have done everything on our side that Comcast needed including providing data and working with them to get to a resolution. They are pushing out the fix as fast as they can. At this point all we can really ask is that you wait for them to provide the entire update to resolve the issue."

@Xfinity Support any response to the above emails from Motorola?

Edit: btw their gateway is trash. The wifi speeds are about 300 Mb/s slower and the range is far less than my own router.

Same issue here. Been going on for months. 

Also posted this on this thread: https://forums.xfinity.com/conversations/your-home-network/mb8611-firmware/63886b8a39eb3658cfbb7083

I guess I am a bit late to the sad party, but I am having the same issues. I've been having these issues consistently for the last 6 months, maybe longer tbh, but I don't remember when they first started. 

Here is what I've done so far, but again, the problem still persists.

1. Had Comcast run a new line from the pole into my house (to be fair the line was probably 10-15 years old)
2. Had Comcast replacee a peice of hardware on the line, where my cable line plugged into
3. RMAed my modem with Motorola and replaced it 2 weeks ago (took a little back and forth with them but not a long time)

Today, I spent 1.5 hours with the most technical Comcast Tech I've worked with so far and basically he found nothing. He checked pretty much everything, and showed me everything he was checking. We compared all that he was checking with my "Connection" info (from the Motorola Admin screen) and everything seemed great. 

I never thought to check the version number of the modem's software, but I am currently on 19.2.18 (I hard reset my modem today tho)

I hard reset my modem today, so unsure if this was the a different version before this and I don't know what version I was on with my older peice of hardware. Either way, this is really disappointing becuase Comcast should not recommend this hardware (obviously this is an issue) and Motorola should not sell it (or both Companies should ideally fix it, but that doesn't seem like it's going to happen). 

My next steps are to try another non-Motorola modem - either by renting or buying a new one and trying to return it before the 30 day mark (or sell the Motorola one online). 

If anyone has any questions, happy to answer.