I bought the plugin yesterday. Everything works fine on my side in terms of compatibility, etc. The problem occurred during online testing. So we opened the server on port 7070. We created an itch.io page and used another PC to download our game to test the connection. We are already on the same connection, but it is impossible to connect via the other computer. However, everything works on the PC hosting the server.
All firewalls are disabled, and public connection authorization is enabled.
I'm out of ideas. I thought it would be plug and play, but now I have to learn CMD, and the plugin doesn't come with a tutorial or a readme file. :(