Connecting to local hosted server

[Pezin-chan]

When I host a server from my pc, friends can connect just fine, but because my router doesnt have NAT loopback, I have to connect via the command. Im used to that, thats fine. But when I do these commands in the console (many variants, such as "connect internal ip", then "connect internal ip:port", or "connect localhost" etc.) either its a black screen and I need to do "disconnect" in the console, or its the "awaiting state" or something on the screen, to infinity, and in the end, I also need to disconnect by the console.