I normally don’t do Windows but to day I helped a customer troubleshooting Problem with a Windows based DHCPv6 Server.
Here is the setup:
Client — Catalyst 3750 —– Windows DHCPv6
DHCPv6-Realy was configured on the 3750
Using Wireshark on a mirror port on the 3750 I saw all the DHCPv6 request from the Relay but no answers from the Server.
After some time with google I found this article from Microsoft. Now everything is working.