pfSense

WAN interfaces configured for DHCPv6 prefix delegation have a known prefix structure that can be used when configuring OpenVPN server tunnels, but unlike 6rd (resolved in #16706), there is no equivalent option for DHCPv6-PD. Users with delegated prefixes (e.g. Comcast /60) must hardcode an IPv6 tunnel network prefix, which breaks silently when the delegated prefix changes.

Add an option to the OpenVPN Server IPv6 tunnel network settings to track a DHCPv6-PD WAN interface and prefix ID, deriving the /64 dynamically at config-write time and updating automatically via rc.newwanipv6 when the delegation changes.

A working patch against 25.07.1-RELEASE has been tested and verified on pfSense Plus (arm64) with a Comcast /60 delegation.

Screenshot of what my config UI now looks like also attached.