Be glad it’s not in your area or you were grandfathered into unlimited then. 1.2 TB cap with $10 / 50GB over that. Or you can get unlimited data for an additional $30 / month. Their modem rental includes unlimited data for $25 / month.

You might also want to run a speed test. Comcast has a very small list of modems that they approve for mid split / high split for faster upload speeds https://www.xfinity.com/support/internet/customerowned That meant my own modem (which supported it but wasn’t “approved”) could only get ~100 Mb/s upload, but their rental hits the 300 they advertise (closer to 350 with the over-provisioning)

Except with their bandwidth fees I would be paying more money to use my own equipment than to rent theirs (which includes unlimited bandwidth). Not to mention there are very few modems they allow to use DOCSIS High Split for increased upload speeds even if they’re capable of it.

Put it in bridge mode, open it up and disconnect the wifi antennas and use your own gear.