Intermittent Internet Modenm Connectivity Issues

The upstream power is too high / out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting 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 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

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.

Thanks for the reply!

Since I posted this question, I've spent countless hours on phone support going through useless remote test after useless remote test.

Support told me to upgrade my modem, which I did to the very latest.  No improvement.

I've eliminated splitters of any kind, and plugged the coax coming into the house directly into the cable modem. No improvement.

I think that I've finally made it into next level support, which is supposed to be investigating the problem remotely, and if they can't figure things out will supposedly send an actual repair person out to investigate.

O/k good luck with it ! Please post back here with how things turn out.

P.S. Also 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.

Here are the modem status values from the pinned "Internet Troubleshooting Tips" post at the top of this board;

Specification      Min             Max

Just out of curiosity (and for others stumbling onto this thread), what is an acceptable range for power levels on the upstream channels?

So I just looked at the stats for my new modem (XB7)...

For the xb7 modem, it appears that (according to your table), the DOWNSTREAM power levels and SNRs are out of spec, but upstream looks OK.  I've already sandpaper-cleaned the copper on the coax, and eliminated any splitters that I can find.  I'm assuming this means that I will need to wait for techs to diagnose beyond the house.

The SNR is fine. Re-visit the chart. There is no max SNR. Higher is better. Yours is very good. The downstream power level is now kind of high, but it still may or may not be a problem. Looks like you improved the connection.

You could try using a minus -6dB Forward Path Only attenuator pad such as this one to knock that downstream power down by the same amount;

https://www.amazon.com/line-Signal-Forward-Attenuator-FPA6-54/dp/B07882H96R

It will not affect the upstream power which is now in spec. They make a 9dB one as well. Or you could let a tech properly balance the line.

This may or may not be the direct cause of the problem. YMMV. Good luck !