user_rf4130's profile

Visitor

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8 Messages

Thursday, January 12th, 2023 10:55 PM

MB8611 T3 timeouts and timing synchronization failures lead to frequent disconnects

Over the past week or so, several times a day my MB8611 modem will disconnect and restart. Looking at the event logs, it is due to either T3 timeouts or timing synchronization failures. I'm on software version 21.3.7, which many others seem to be having an issue with on this device. Would it be worth calling a tech out to check on wiring?

New Poster

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5 Messages

14 days ago

Just want to let you know this is happening to me too.  Everything was fine until I upgraded to the MB8611.

Official Employee

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503 Messages

12 days ago

Hi there and welcome to Comcast. Thank you so much for reaching out to us about your service issues. You are in the right place and I am happy to asssit you today. Are you on a wired connection or hardwired connection?

Visitor

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8 Messages

@XfinityRoberto​ Usually wireless but I have switched to wired since I started having issues and it has not helped. Actually today I started seeing unexpected errors on downstream QAM256 channels:

Official Employee

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817 Messages

Thank you for keeping us posted, @user_rf4130! If you're seeing several T3 timeouts, that usually indicates a signal issue that a technician will have to troubleshoot on site. 

Please send a direct message by clicking the chat icon in the upper right corner of the page, click on the pen and paper icon, then enter “Xfinity Support” in the “To” section. Please include your name and address and I'll be happy to help :). 

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Visitor

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8 Messages

The past few days I'm seeing "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW" frequently along with disconnections.

Visitor

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8 Messages

Upstream power levels have risen to the low-50s dBmV. I have a tech coming out tomorrow and will post an update afterwards.

Visitor

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8 Messages

6 days ago

For others folks following, as an update, a tech came out yesterday morning and replaced the length of cable running from my wall to my modem, removed a splitter, and got the upstream power within spec (low 40s). Downstream is in spec but on the high sides 9-13.5 However the past two afternoons I continue to experience drops related to:

"SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing"

It seems to happen more frequently toward the end of my work day. Happened 3-4 times in the past few hours. Very frustrating during work meeting/calls.

I have another tech coming out tomorrow afternoon.

(edited)

Visitor

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12 Messages

@user_rf4130​ Already had a tech do all that here. Still disconnecting 

Visitor

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8 Messages

2 days ago

The second tech replaced the rest of the cable run between the house box and the modem and added a forward path attenuator to get downstream power close to ideal (3-5 dbmv, down from 11-13 dmbv). Still had disconnects at the same rate.

Had a third tech visit today - he said the neighbor's rented modem doesn't have any disconnections logged, which eliminates street-side issues, so the only parts left are the line from the street box to the house box, and of course the modem itself. He installed a temporary above-ground run between the street and house junction boxes. I've seen a couple disconnects since he's left, so it's either the modem or the modem firmware Comcast is pushing (which other MB8611 owners are theorizing, as there's an influx of similar posts since the new year on this forum regarding this model).

I have an Arris S33 on order and hopefully that will be the end of this. Unfortunately no option to return the MB8611.

More logs in case any engineers are looking:

(edited)

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