This is not specifically related to OPNsense (I think), but there are a lot of knowledgeable people on this forum so I thought I'd ask anyway.
For the past week or so, I've noticed that my Windows 11 PC is not renewing its IPv6 address. I have a /56 prefix delegation from my ISP which is split into a few /64s on my OPNsense box and handed out to clients using DHCPv6. I'm running ISC DHCPv6 in Managed mode because I want to control the IPv6 addresses assigned to clients (no SLAAC). This has worked fine until recently. Now, my sole Windows 11 PC won't renew its IPv6 address. Upon expiration of the DHCPv6 lease, it reverts to an fe80: link-local address and I lose public IPv6 connectivity. Doing ipconfig /renew6 causes the PC to pull a new lease from OPNsense, and all is good until the next time the lease expires.
Any ideas what's going on here? The problem started around the time I upgraded OPNsense to 25.1.6 (which introduced DNSmasq for DHCP), but I haven't changed my configuration and am still using ISC for DHCP. DNSmasq is disabled. I simply upgraded without changing anything in my configuration. My other clients (Linux, Windows 10, macOS, iOS) can all renew their IPv6 leases without issue as before; it's only the one Windows 11 box that has an issue. So I don't think it's related to the OPNsense 25.1.6 upgrade.
Thanks!