Upgrading and activating a modem

I have a new modem (Motorola MB8600) that will replace my current one. I think I’ve followed all the instructions on connecting the new modem and visiting xfinity.com/activate, as well as calling 1800-xfinity. Either way, the equipment doesn’t seem to be visible to Comcast. The browser (with LC connected directly to the modem) doesn’t bring up any page (I think it should be bringing up and activation page). And when I call, the automated voice system for activating a modem says it doesn’t see any equipment that needs to be activated on my account.

My question is how can I replace and activate my modem. I can’t seem to find a way to talk to a human and the automated system isn’t seeing my new modem when it’s hooked up.

Also, on my modem, I show two solid blue arrows and the solid blue globe, which I understand to mean that downstream and upstream are bonded with 2+ channels and the modem is online with DOCSIS 3.1. So, not sure why Comcast can’t see the modem and help activate it.