xfinity apple airport randomly does not provide ip4 only ipv6 NAT

I have a long standing issue with the apple airport provided by xfinity. Randomly my computer cannot access the internet, and I tested with multiple computer when this happened, and none of the can access the internet with ipv4, only websites that allow ipv6 connections will work. It randomly comes and goes, reboot it a couple times and finally ipv4 will work again for a while and then stops again. xfinity support was woefully unhelpful and didn't even seem to understand the difference between ipv4 and ipv6. Unfortunately this affects access to the majority of websites including my work VPN that I cannot connect to when this happens. Has anyone seen this and found a fix for it?