Regular interruption of service with CMSTATUS:DS_Diplexer_Mode_Change_Ignored: and UCD invalid or channel unusable; MODEM log messages

@user_cdf06d 

Don't post that private info here on the public forums ! Send that requested info to them via a private / direct message. Here's how;

Click "Sign In" if necessary.
 
Click the "Direct Message" icon  in the upper right corner or https://forums.xfinity.com/direct-messaging  
 
Click the "New message" (pencil and paper) icon.
 
The "To:" line prompts you to "Type the name of a person". Instead, type "Xfinity Support" there.
 
As you are typing a drop-down list appears. Select "Xfinity Support" from that list.
 
An "Xfinity Support" graphic replaces the "To:" line.
 
Type your message in the text area near the bottom of the window.
 
Press Enter to send it.

[Permission from and credit given to BruceW].

@EG​ I put the character X in place of all the digits of the MAC addresses in my post. At least I thought I did, perhaps I missed one. Anyway, thanks for the reminder.

@user_cdf06d​ 

It's public now.

@user_24f3a2​ Yes, I'm running an MB8611. I've asked Motorola to exchange mine with a new unit of the same model to see if that helps. Failing that, I may need an on-site visit from Xfinity. 

So... I ran an 8600 & 8611 next to each other on a splitter, the 8611 has been rebooting, but not the 8600. That tells me the modem is bad again.

I RMA'd it over a year ago and it was fine until recently. I had Xfinity out multiple times a year ago, and they told me it was my modem - I didn't believe them, but finally connected my old 8600, and they were right. The RMA process was pretty painless.

All of that being said, I've ordered an S33. Good luck with the new modem! I hope it helps.

At this point, I can definitely say my original 8611 was spontaneously rebooting due to an internal fault,  and that the replacement does not do that (current uptime is 7 days 21h and counting).  Based on user_24f3a2's message, I feel that the rebooting issue may be latent in this model and therefore similar failures could reoccur a few months down the road on the replacement device I now have. I have a new S33 waiting to be pressed into service should the rebooting issue on my 8611 recur.

I *also* have line quality issues going on, and have set up an appointment with a Comcast Technician to correct this soon.  As the replacement 8611 has shown, it is possible (and expected) that marginal line conditions should not cause unpredictable reboots. However, both issues must be addressed to ensure robust internet service going forward.

I hope this post helps someone. 

Hello @user_cdf06d. Thank you for the update. I'm happy to hear the new replacement modem is not doing the same thing the previous one was doing. How did your tech appointment go yesterday afternoon? Was the tech able to identify an issue on the line and escalate your issues to the maintenance team?