I get sent to the modem reactivation portal on a nearly daily basis since I've signed up. I've already power cycled all the devices, modem, router, and computer. I've called several times and none of the support reps I've spoken to have been able to identify the source of the problem. The issue occurs on all of the internet connected devices on my network (phone, laptop, TV, gaming consoles).
On a about daily basis, I get redirected to https://register.be.xfinity.com/activate?channel=WALLEDGARDEN
Since I've done it, I get the following error:
"Sorry, we can't find this device. Please give us a call at 1-800-xfinity.
We'll add this device and activate your service as quickly as possible."
Call in and ask the next rep to completely remove the modem from your account and to "re-provision" it from scratch. Also ask them to confirm that the provisioning and account data in their database is correct and complete.