i have already deleted the tunnel completely.
As soon as I try to create a new peer via the GUI and then start the WG server, it immediately shuts down again.
Edit: The problem seems to be when I try to create a configuration for ipv4 and ipv6.
Unfortunately I can only create a configuration for ipv4 only.
But since I have a cgnat connection I am dependent on ipv6. But with the older versions it still worked.