Review on xFi Pods WiFi Range Extenders - Exclusively Compatible with Xfinity Rented Routers, not Customer Owned Routers (1-pack Single Pod, in White) by Kelly Kunkel

The modules basically repeat the signal from your main router, they also receive the signal from each other, but they don't work in all cases. In my case, my powerful TP-Link router worked better because the modules were weak and the signal was unstable. Xfinity Support checked this and came to the same conclusion. When they work, you can move seamlessly from room to room and not have to worry about changing the IP address. Xfinity and Revain have good return policies, so they're worth a try.