Internal Ip as a server IP :S

Ok i have no idea what i did cause i had a multiplayer working the other day.
However, this time i made it just how i did last time by clicking on create multiplayer and invited my friend and it didn’t work. I noticed that the Ip address for the server was an internal Ip address so how can i fix this.

Thanks for all the help to come.

Go onto any whois site and find your own IP. For example

You can then give your friend that IP to search for.

I tried giving him the IP address that appeared in the garrys mod Console that wasn’t and external one. But it still didn’t work.