Aris SB8200 unable to connect to internet even when all lights are solid and correct MAC and serial number in the Cox system.

I am a new customer and I am trying to use an Aria SB8200 that I had previously used with Xfinity. I factory reset the modem and it boots to completion showing all solid lights, but I am still unable to connect to the internet. I am able to reset my router through the Cox web service. Was on the phone with Tech Support all evening and they weren't able to make it work on their end. Is it the cable modem? It was working perfectly with Xfinity and it is on the list of modems that Cox says will work.