Comcast AT&T IPV6 / DHCP

I have been asked by upper management to utilize SMB Modem business solutions from AT&T and Comcast for our backup lines at our various sites.

I get everything working with statically assigned IPv4 addresses, however, they do not offer static IPv6 addresses.   However, I was told that I could get an IPv6 address on the WAN2 interface via DHCP.

However, I keep getting /128 IPv6 address on the interface that isn't accessible from the outside world.   After a lot of googling I am no closer on how to update my configuration to work with Comcast and/or AT&T.

Can anyone point me to the correct direction on this?