I demand my /56
This class-action will be in two parts:
AT&T doesn't have an escalation process to take responsibility for their customer premise equipment. If at the end of the call to tech support regarding a bug in the behavior of their CPE, you are forwarded to their pay-per-incident support for which you pay $59.95 for them to forward you back to the same tech support call center.
The two CPE options for GPON fiber was the BGW210 and the current BGW320. Both contain broken behavior with the DHCPv6 server offered to the pass-thru third-party router. For any request of a prefix delegation length, a /64 is returned. As a /64 only represents a single address block, it is useless for subnetting. The best-practices recommendation is to offer a /56 (256 address blocks) for residential service.