Modem

The concern is not "Xfinity App" help related. Topic moved here to this help section for assistance. 

Hello @user_0df528, Thanks so much for taking a moment out of your day to leave a post on our community forum. That is a great question! Please check out these links below for more information:

Using Approved Third-Party Equipment for Xfinity Internet and Xfinity Voice: https://www.xfinity.com/support/articles/list-of-approved-cable-modems

Benefits of Renting an xFi Gateway: https://www.xfinity.com/support/articles/why-rent-wireless-gateway

Overview of Xfinity Gateways: https://www.xfinity.com/support/articles/broadband-gateways-userguides

Here's what you're going to run into with your own modem, Xfinity will claim up and down that you need their rented modem to solve 9/10 of any problems that occur with your modem,[Edited: "Inflammatory"/"Language"]. It's typically an issue with their equipment down the line behind your equipment causing the issue. And if it's not the other 1/10 they've likely pushed a bad configuration or firmware update to your device, and then they'll claim they don't do that but it's happened to me twice and I had logs from my modem to back it up as proof each time. I ended up filing a BBB claim against them and they FINALLY admitted they broke my modem, I even placated them and bought a top of the line "xfinity approved" modem on their list, and guess who's back to having the same old issues because it was never my modem?

Modems aren't that incredibly complex, they don't just "break" they may overheat and die but for the most part they're a set it up and forget it device unless your ISP is having issues or causing issues. Just be warned these are their tactics and you have to escalate your issues to higher tiers to get any real answers or fixes out of them, [Edited: "Solicitation"]

Sorry for the rant but more people need to be aware this [Edited: "Inflammatory"]