IPv6 - Fixed Suffix, Dynamic Prefix

[xeonixo]

Is your feature request related to a problem? Please describe.
The public IPv6 prefix with a defined suffix should be possible.

Describe the solution you'd like
a possibility to set a custom IPv6 suffix in the configuration (e.g. ::aaa1). My container and the reverse proxy have the same public prefix. At the end, the updater with address 2100:123::1234:abcd should publish the address 2100:123::aaa1 for the DNS record.

Describe alternatives you've considered
none

Additional context
I work with MAC VLANs and would like to publish the address of my reverse proxy. Unfortunately, I have a dynamic prefix. The suffix always remains the same. For example ::aaa1. I would like to make my reverse proxy public, otherwise either my server IP or even the IP of the router would be used.