Switch from UPnP to port host

[tough mango]

I downloaded this git repo and waned to switch from UPnP hosting, which it uses, to something normal like running a server with a port which I can forward. UPnP isn't working for me and likely for most of Germany as well. Here's a snippet of the UPnP Setup. Git repo cloned: https://github.com/devloglogan/MultiplayerFPSTutorial

I am getting this error with UPnP even though I enabled it in my router, likely because I dont have a dedicated Ipv4, most of Germany doesnt