Xfinity pro extender can’t set up

I’ve recently become an Xfinity customer and I got a new modem and one pro extender to cover the dead zone in the house. The modem set up was very easy. However I have tried every area of the house and the extender gets stuck on step 5 with the QR code. I scan it and it thinks for a bit then says sorry the app cannot set up to the extender. It has a solid white light in every room but offers no service. Which sucks because the only area of the house that I can put the modem is on the extreme far end so that leaves a large portion of the house with 5-7 mbs speeds and minimal connection.