The client or the server can connect to each other. If you manually manage port forwarding for the client, you'll need to forward ports 9000-9002 for UDP traffic. Once you forward those ports to UDP traffic on your router. If you want multiple connections, you will need to open more ports (three for each connection). We recommend opening 9000-9040 in case you want to have a bunch of friends connect to you at some point. You can add the starting port in Advanced Settings or change it on your networking settings tab on the app.