I know it's possible to have more than one dynamic IPv4 address for my equipment using customer-owned equipment. I have an Arris SB6190. In other systems, the ISPs usually allow up to 3 CPE to get an IP address through a single modem. However, with Xfinity, the default is only one. Additional public IP addresses for residential circuits is an unusual request, and I have not been able to find anyone on the phone who knows how to do it, probably because their tier-1 is limited in scope. "Additional IP Addresses" is listed on the rate card for $4.95/month for residential Xfinity. How do I get the 2nd IP address?
You can't do it with that modem. You need a modem with two ethernet ports. Even then, it's not guaranteed because this is a feature that they are phasing out..