DHCPv6 server not sending REPLY to Macs

[Croce, Lucas]

I've been troubleshooting an issue where Macs have not been working on IPv6 enabled networks because they are asking to use the same IPv6 address they had previously which is not allowed either because it's from a different VLAN or it's been assigned out to another client already.  Apple support claims that the DHCP server is not following RFC 8415 Section 18.2.3, which states "If the client receives no responses before the message transmission process terminates, as described in Section 15, the client SHOULD continue to use any leases, using the last known lifetimes for those leases, and SHOULD continue to use any other previously obtained configuration parameters."

My understanding is that the authoritative flag in the dhcpd6.conf is what should do what is described but I can clearly see in a packet capture taken off the client that the DHCP server is sending a REPLY to the CONFIRM message from the Mac.  Any ideas on what I'm missing?
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