The host of the game needs to forward 4976 UDP in order for others to connect.
You can double check the port with the Successfully bound socket to localhost: xxxx! message where xxxx is the port you need to forward.

Go to continue to main menu from the Plutonium menu

Go to custom games, pick your map and start the game, you must be in game for your friends to connect, it will not work from the lobby!
Also if you experience the message “waiting for more players” you can use the following command to force start the match: xpartygo

Friends join by opening the console, they MUST BE on the Pluto main menu and wait until “Downloading Playlists …” is gone, then they can type the following, replacing YourIP with your public ip. connect YourIP: 4976
If you don’t know your public IP any website like whatsmyip.org will work.
Explain more specifically

Thank you in advance