Thanks for the reply. After being told not to use snap and wanting to do it right from the start, I tried migrating to Debian and tested the networks.
In the process, I broke the snap Docker installation. Now I’ve installed Debian and manage everything with Portainer. Changing the bridge IP (BIP) also worked.
Nginx is running, OpenVAS is running, TeslaMate is set up, and then some other unnecessary stuff. I think Portainer is the right solution for beginners.