I do not have new equipment and this is happening to all my devices Laptop, mobile devices, Ipad. getting redirected to the activation page. My equipment has been activated for 14 months. This have been case for the last couple of months after when I discontinue and re-joined xfinity internet.
Call 1-800-comcast and ask a 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.