According to threads on Microsoft’s Developer Network, DHCPV6 has been broken since the first deployments of the Anniversary Update last August. I first noticed an issue on October 4 where several Windows clients would no longer register their IPV6 DNS address post update.
While this has been broken for a couple of months, I was advised today by Adam Rudell, a Microsoft Support Escalation Engineer, that the “PG is actively investigating. I just updated the TechNet thread and will follow up as soon as PG has provided me some more information.”
The full thread can be read here.