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user_917g09
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Friday, September 19th, 2025

Years Of Constant Signal Drops

Hello,

We've had constant signal drops for years now on our Xfinity network. I've swapped out modems and routers. I've had multiple techs out, including one that recently ran new cable from the outdoor box into our home. And yet we still get drops every day, sometimes as bad as every hour or two while at other times it will seemingly be fine for a stretch of days. Makes it very difficult to track the issue, but nobody I've spoken to has seemed very interested in diagnosing the problem, only running through the checklists of what it "usually" is for other people. And that's with multiple support folks admitting that they can see "hundreds" of signal drops on their end.

Using a Motorola MB8611 and Eero Max 7 for my network. When it's connected, it's great. Gigabit speeds, all that. Would just love for it to work "most" of the time.

Here's the log I pulled from my model, you'll notice all the critical errors. Full MAC digits are redacted.

Any help is much appreciated. Thank you.

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

02:26:59
Tue Sep 16 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

00:48:06
Wed Sep 17 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

07:56:04
Wed Sep 17 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

09:47:44
Wed Sep 17 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

13:37:57
Wed Sep 17 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

14:19:29
Wed Sep 17 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

18:54:22
Wed Sep 17 2025

 

Critical (3)

 

Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

20:50:13
Wed Sep 17 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

10:52:25
Thu Sep 18 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:90:f0:31:0e:00;CM-QOS=1.1;CM-VER=3.1;

   

12:55:07
Thu Sep 18 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

Time Not Established

 

Notice (6)

 

Honoring MDD; IP provisioning mode = IPv6

   

21:35:32
Thu Sep 18 2025

 

Notice (6)

 

DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

   

21:35:41
Thu Sep 18 2025

 

Critical (3)

 

UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;

 

EDIT: Here is what our downstream signals look like...

Downstream Bonded Channels  
  
   Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked QAM256 20 975.0 -5.5 41.5 0 0
   2 Locked QAM256 1 387.0 -1.8 44.5 2 0
   3 Locked QAM256 2 393.0 -1.4 44.7 1 0
   4 Locked QAM256 3 399.0 -1.6 44.4 1 0
   5 Locked QAM256 4 405.0 -2.1 44.3 1 0
   6 Locked QAM256 5 411.0 -1.9 44.5 1 0
   7 Locked QAM256 6 417.0 -2.6 44.1 2 0
   8 Locked QAM256 7 423.0 -2.2 44.4 1 0
   9 Locked QAM256 8 429.0 -2.0 44.5 1 0
   10 Locked QAM256 9 435.0 -2.3 44.3 1 0
   11 Locked QAM256 10 441.0 -1.9 44.6 1 0
   12 Locked QAM256 11 447.0 -2.2 44.5 1 0
   13 Locked QAM256 12 453.0 -2.2 44.5 1 0
   14 Locked QAM256 13 459.0 -2.3 44.3 1 0
   15 Locked QAM256 14 465.0 -1.9 44.6 1 0
   16 Locked QAM256 15 471.0 -2.4 44.3 2 0
   17 Locked QAM256 16 477.0 -2.2 44.5 2 0
   18 Locked QAM256 17 957.0 -5.5 41.6 0 0
   19 Locked QAM256 18 963.0 -5.4 41.7 0 0
   20 Locked QAM256 19 969.0 -5.1 41.8 0 0
   21 Locked QAM256 21 981.0 -5.9 41.1 0 0
   22 Locked QAM256 22 987.0 -5.7 41.6 0 0
   23 Locked QAM256 23 993.0 -6.1 41.1 0 0
   24 Locked QAM256 24 999.0 -5.5 41.1 0 0
   25 Locked OFDM PLC 193 774.0 -4.9 41.5 20131063 0

Question

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Updated 

55 minutes ago

 • Edited

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XfinityDuron

Official Employee

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179 Messages

17 hours ago

Hello there, I understand how this issue can become very frustrating. What is the current state of your Internet services? 

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0

user_917g09

Visitor

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3 Messages

Thanks for responding. Services have been the same since posting, multiple critical errors a day shown on the logs, with...

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

and

"UCD invalid or channel unusable"

Showing up most often. Any help you can provide would be greatly appreciated.

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17 hours ago

0

XfinityAmandaB

Official Employee

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2.6K Messages

 

user_917g09 If you could send our team a direct message with your full name, the name listed on the account (if different), and the service address associated with your account, I'd be more than happy to look into this for you. To send a Direct Message, please click on the chat icon in the top-right corner of the screen, next to the bell icon, and then type or select "Xfinity Support" to initiate a direct message.

 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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16 hours ago

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user_917g09

Visitor

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3 Messages

Just sent the requested DM. Thank you.

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6 hours ago

0

EG

Expert

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113.4K Messages

55 minutes ago

@user_917g09 @XfinityAmandaB 

Please circle back here and post any possible solutions for the issue here in these open public forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.

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