GaticoWeed don't hijack other peoples posts. Host must already be in a game and you must join them through F10, as there is no party system for T4. Read here. https://plutonium.pw/docs/custom-games/
CodWawer
i had same problem (i put my own cfg)
just delete plutonium_mp.cfg
located:
C:\Users\ (your user name) \AppData\Local\Plutonium\storage\t4\players