Loses connection from my friends server

[MrJuan02]

Hello, me and my friend just bought this game. Not a long time after we created a server we started getting som issues with the connection. If he makes the server then i loses connection after a while playing, and if i make the server then he gets disconnected. And my friend is using fiber and im using a wired network so i dont know why this should be a problem. Please help if you know somthing thanks.