> I often appear blurry or the sound cuts out to them, especially if I’m on WiFi.

If it works fine wired, but not on wi-fi, then your wi-fi signal is the problem, not asynchronous upload bandwidth.

Don't get me wrong, the 10% upload is atrocious, but not the culprit in this case.

The last comcast 2-in-one modem I saw at a neighbors was a piece of crap. No external antenna's, signal wouldn't cover a 2 bedroom ranch. PSA - and this may be out of date - you should be able to buy your own modem and router and it will pay off in a year vs "leasing" their crap equipment for a fee every month.