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

Responses

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XfinityDuron

Official Employee

•

258 Messages

24 days 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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user_917g09

Visitor

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6 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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24 days ago

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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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24 days ago

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user_917g09

Visitor

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6 Messages

Just sent the requested DM. Thank you.

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24 days ago

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EG

Expert

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113.9K Messages

23 days 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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user_917g09

Visitor

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6 Messages

Will do. They are following up tomorrow after some local maintenance is finished.

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23 days ago

EG

Expert

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113.9K Messages

@user_917g09

TY !

I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Please mark an Accepted Answer! tick

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23 days ago

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user_917g09

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6 Messages

19 days ago

UPDATE: They weren't able to find the issue through DM so I have an additional tech coming by to check things out again. They previously ran some new line earlier this month but are looking to see if they missed something.

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EG

Expert

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113.9K Messages

@user_917g09

Good luck !

I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Please mark an Accepted Answer! tick

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19 days ago

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user_917g09

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6 Messages

12 days ago

UPDATE: Tech came by and replaced our splitter and removed an amplifier in our interior panel. They made no attempt to understand the issue and just said that would "fix it".

Signal was OK for a couple days while I monitored, but have been getting the same Critical errors on my modem's event log the past three days. Both T3 and T4 timeouts. Worse yet, now both my cable boxes are getting error codes, and after spending another 5 hours DM'ing back and forth their solution was to send another tech out even though I told them I had this same issue last Fall and one of their advanced tech folks found a fix on their end. This time they just tried a bunch of reset signals, same thing I can do myself on the app, and threw their hands up.

Error codes are RDK-03033 and RDK-10000. Don't know if it's related to what the previous techs did in my home when trying to fix the dropped signals.

Does anyone have suggestions here? I thought going through the forums and getting the DM's would get me to more advanced support, but it seems to be the same thing as the phone lines. Doesn't feel like anyone has made even a remote attempt to understand the issues or communicate what is going on, it's just repeating the same cycle over and over.

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Your Home Network

user_917g09

Years Of Constant Signal Drops

XfinityDuron

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XfinityAmandaB

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EG

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EG

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EG

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