Visitor

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1 Message

Saturday, June 27th, 2026 6:39 AM

Intermittent outages with DOCSIS T3 timeouts and UCD errors

I’m having intermittent internet outages. Automated checks say the modem is online, but my NETGEAR CAX30 event log shows repeated DOCSIS errors:

- Critical: UCD invalid or channel unusable
- Critical: SYNC Timing Synchronization failure
- Critical: Started Unicast Maintenance Ranging - No Response received - T3 time-out
- Warning: MDD message timeout

Signal levels are borderline: upstream transmit power around 48.8-50.3 dBmV and some downstream channels down to about -8.3 dBmV.

Can an Xfinity employee please check the line/signal history, upstream noise, tap/drop, and schedule a technician if needed?

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Expert

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118.8K Messages

2 days ago

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/reconfigured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.

Also, check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, or animal chews.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.


Good luck with it !

Official Employee

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1K Messages

8 hours ago

Good morning @user_dq7570, and thanks for reaching out to us on the community forums, I hope this message finds you well. I am sorry to hear about your connection issues. As someone that works from home I can understand the importance of having a reliable connection, and you have come to the right place for assistance with this issue. I see you have already sent us a direct message. In the future, please wait until instructed to do so because sending unsolicited Direct Messages to an Official Employee of the Xfinity Community Forum is a violation of Forum Guidelines, but we will work with you there.

Expert

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118.8K Messages

4 hours ago

@user_dq7570 

Have you had a chance to see if any of those tips apply ?

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