Hello - we recently procured a new modem, and the new modem is not yet listed on the "Devices" page within Xfinity. As a result, in our attempt to return the old modem, the old modem is similarly not listed on the "Returns" page, as Xfinity has no indication that we have two modems at this time. How can I proceed in returning the old modem? Additionally, how can I ensure the new modem is properly listed on the Devices page, so as to avoid problems moving forward with Xfinity's knowledge of our current devices? Thank you so much!