Plutonium

Dss0 I am using the invite function, they invite me, and I can not connect at all

Hey, I got plutonium quite a while ago and was playing custom games with my friends yesterday, but today I could not join. I did all the steps from the customs games/playing with friends document. Nothing helped. I made sure to port forward, and made sure the UPnP was enabled on pc and router. The UPnP shows disabled, port 0 and it says UPnP does not work.