Modem

I'd suggest checking "My Device Info" whenever it comes back online.  Presently I can't access it.  Also don't know the link but this page Using approved third-party equipment with Xfinity Internet and Xfinity Voice links to it if it ever starts working again.  Presently it's doing...

Once that page starts working again you can look.

The one big thing I'll suggest is make sure whatever you get is a DOCSIS 3.1 modem and on the list for faster/enhanced/whatever upload speeds.  Last I checked some older DOCSIS 3.0 modems were still supported, but they're getting phased out and buying one now is a waste of $ even if it's cheap.  Also make sure it's on the list for DOCSIS 3.1 upload.  If it's not your upload will be capped at ~35mbps on the most expensive plan, while a cheap plan will get much better upload with a supported modem.  Then DOCSIS 3.1 modems have to be approved to get the faster upload.

I have voice service and use a Netgear CM2050V.  Works pretty well, and gets the faster DOCSIS 3.1 upload speeds.  So that works, but can't even look at what else works right now.  There are a couple other supported models with voice support IIRC, combo units with WiFi built in last I checked.  I'm also wondering if this outage is preventing people with Comcast gateways from changing settings.  Can't test that either since I don't have one.