But why can my other friend join?You need to open your ports so he can connect to your server.
No one of us are on the same network.He's probably under the same local area network, I don't know.
I'm so confused with what your problem is.
You are hosting the server, right?
Friend 1 can connect to other OTs but not yours.
Friend 2 can connect to other OTs, including yours.
Is that what the problem is?