Netgear CM700 only has IPv6. No IPV4 access

I have a Netgear CM700 modem hardwired to my laptop. I have activated the modem through a comcast rep on the phone. They can see the modem, reboot it, everything. Now, I can only access sites like Google.com, facebook.com, youtube.com; sites that have IPv6 enabled. I cannot connect to any site that has IPv4. I have gone through multiple tiers of tech support; Internet Specialist, Advanced Repair, even a Netgear representative. Noone can figure this out.