Arris modem doesn’t acquire IPv4 via DHCP

I recently purchased an Arris surfboard SBG7600AC2 that I foolishly hoped I could easily use to replace the Xfinity modem I was renting.  Well, after going through the process of chatting with Xfinity support I registered my new modem.  The old modem stopped working so I plugged the new modem in.  My new modem (which is an integrated modem/router/WiFi AP) is in routed mode and is pulling a /60 IPv6 prefix via prefix delegation.  I can talk to any site on the magical Interwebs that speaks IPv6 (like Facebook or Google or Yahoo!).  However, my modem cannot acquire an IPv4 address for its WAN interface so I cannot go to any sites that use IPv4 (so like 75% of the sites I need to go to - including my work VPN).  The part that has me wondering is that my modem’s status reports “Computers Detected: staticCPE (1), dynamicCPE (0)”. I don’t think that “Computers” in this case means my personal computer.  I have nothing wired into the LAN ports of the modem.  This number also doesn’t refer to wireless devices because the value doesn’t change regardless of how many wireless devices have attached to the Arris WiFi.  So, first, does anyone know what that means.   The second weird thing is that my modem reports “DHCP Attempts to obtain CM IP Address:” = “IPv4 Attempt(s) 0” and “IPv6 Attempt(s) 1”.  So it looks like my modem maybe isn’t even requesting an IPv4 address.  I know that it is definitely configured for IPv4 DHCP.  Maybe I’m misinterpreting that but it sure looks like “Attempt(s)” means “tried” vs “succeeded”.  I talked to Arris support to confirm that this modem is dual stack and should be pulling both.  I couldn’t imagine that this could be sold to the public if that wasn’t the case.  I’m guessing that Comcast needs to fix something in their CMTS but zero chance that anyone at Comcast who I can talk to or chat with is going to know.  I have a tech coming out to the house later but I was hoping to find someone else who has run into a problem like this.