Problem: Wireguard VPN Problem Unifi (Server) and GL-SFT1200 (Opal)

I am running a Unifi UDM-SE at home offering Wireguard VPN Services.
When connecting with my mobile or computer directly to it everything works fine. When connected via VPN and accessing the internet, I am using my “home IP” from the Wireguard Server, as expected.

My Opal has no problems connecting to the UDM-SE, I can see it logging in at UDM-SE Logs and also see traffic on the Opal. This looks good in my opinion.

Problem: When I connect my notebook to the Opal Router (still connected via VPN) and try to access the internet, I do not use my “Home IP” but the one I have on client side.

I think I already tested more or less all configuration options, but it is still not working.
Does anyone have an idea?

Just wanted to add that when using VPN my notebook (connected to Opal) is able to access the UDM-SE Website (local, internal IP in VPN network), but when connecting to the internet websites still show me my local (currently danish) IP instead my home (german) one.