Hi there, Mojang team!

Me and my friends are trying to open a locally hosted server, and we (to our knowledge) opened the correct ports
If you launch the minecraft server.jar file when the "server-ip" field in server.properties is empty, server will start as usual and the host can enter it.
However, if we try to put his public IP in the field, starting the .jar file will launch the CMD (and GUI for a split second) but give an error a few seconds later.

I tried to do the same in my own PC (with ports and all) and it does seem to reproduce, and apparently there have been other people online with the same issue.
Oh, and of course we made sure there were no other instances of the program running, not even Java

Attached is a screenshot of the error, but basically the same bug/issue as ticket MC-228064

Thanks,
Turhral