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

Hello,
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?
BR

Edit:
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.