Modem not syncing to DOCSIS 3.1 level (no blue light)

The upstream power is too high and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, 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, kinks, sharp bends, etc.

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 !

Thanks for the comments. There are no splitters at all as we have only internet and nothing has changed inside in many months (if not years) ... I'll check to see that nothing has disturbed the feed and coax to the modem and, if not, then I'll book a visit ... Thanks!

BTW, the last time I had someone out to work on upstream was many years ago and IIRC when they left they were around 42 dB so something has deteriorated, that's for sure!

Bill W

O/k just bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.

Understood. I know they have to go through their scripts before they can escalate.

Hello, @CTGreybeard, thank you for reaching out in our forum and working with our community to help with your modem issues. I can definitely take it from you here and help you to get things back in spec. In order to get started can you please send me a private message to Xfinity Support with your full name and full address by clicking the chat icon in the top right?

@user_bbfd72

Please create a new topic of your own here on this board detailing your issue. Thanks. The original poster has not returned. 5 month old dead thread now being closed.