Motorola MB8611 dropping connection randomly

First. Is this with a WiFi connection ? If so, for a test, does a computer / device that is hardwired directly to the Netgear router with an ethernet cable have the same problem ?

With this test, we are trying to isolate this down to being either a WiFi-only problem or a problem with the general connection to the Comcast system which would of course affect both. It's a good first step of troubleshooting before proceeding any further. 

It is on a pc that is hardwired to the router.

Wifi never goes out, just loss of internet connection. 

O/k what do the modem's signal stats look like ? Try getting them here; http://192.168.100.1 

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.

Is this what you are looking for?

Yes. The stats are good / within spec. Are there any modem RF error log entries being shown ? If so, please post them as well in their entirety (copy and paste them, don't post a screenshot) but redact the CM MAC and the CMTS MAC addresses for your privacy. They are considered to be personal information. The posting of personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically.

Any more ? If so, I need to see the balance please.

O/k so even though the signal stats looked o/k at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) / an upstream channel / return path impairment somewhere.

There are other signal stat values that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

Personally, I would go with the latter.

I prefer not to recommend particular brands / models of modems, sorry. Just go with one that is compatible with your subscribed to speed tier here: https://www.xfinity.com/support/devices 

Xfinity came by over the weekend and said everything was in the green and looked good. Tech removed a couple filters for multi room dvr that I didn’t need anymore and checked all connections. Now I am not getting the download speeds I was seeing before. So I thought it was the modem but after hooking up my xfi unit I had even worse speed and connection issues.