Most of these methods will work regardless of the kind of router you have. And just in case it jogs your memory, Xfinity has ...

Note that to complete this process, you will need to enter your WiFi network name and password. Restarting your Xfinity ...

Even though I've always advised readers to buy their own equipment, my rented modem and router worked fine, even though I knew in the back of my mind that it was a waste of money.  A monthly charge of ...