DHCPv6 Server - Static Mappings - Leases and DNS resolving

[tryhard]

Hello there,
I have DHCPv6 configured on a tracking interface (changing prefix from ISP).
Have a static mapping with only a suffix ::1000 (like stated in the hint "When using a dynamic WAN address, only enter the suffix part (i.e. ::1:2:3:4).")

The device is accepting this setting and configuring its IP as it should and reachable.

But if I go to leases it shows as "offline" with only the suffix part as address.

Resulting in DNS resolution of the hostname used in the static mapping to be also just the suffix ::1000.

The device is a Fritzbox and doesn't have much options to tweak or debug.

Router Advertisements mode is set to "managed".

Any ideas how to solve or debug this?

[beren]

Still an issue a year later...