New Modem fails to activate. netgear CAX80
I have decided to upgrade my internet. I purchased a netgear CAX80 modem (on xfinity approved list) to replace my current modem and router. Currently have a netgear cm500 modem and a netgear R8000 router. Internet service is fine under current configuration. I Followed the instructions for new modem installation. When using the recommended Nighthawk app, upon trying to activate my modem with xfinity I receive a message saying something has gone wrong contact xfinity. This occurs just after verifying my xfinity account credentials. I also tried using my pc to activate modem with same results. I called xfinity customer support. They went through their script to try and resolve the issue but were not able to. They have scheduled a tech to come and see if something is wrong on my end, but i currently have service with my old modem/router.
Is there something I have missed or overlooked. Any ideas will be greatly appreciated. Thank you.