Get your local IPv4 address
ifconfig -a in the terminal, and copy your IPv4 address.
Go to your
System Preferences->Network and it should say the IP address to the network you connected to.
Open your power shell, and type
ipconfig. Copy your IPv4 address.
Forward your port
At the top search bar in your browser, type 192.168.0.1 to get to your network settings (on Windows you can find this address under your IPv4 titled
Warning! This might look different for you. Go to
Advanced->Security->Port Forwarding and create new. For the port use the one, which you would use for your game. If you haven't got one, be a funny man and use
6969 both for outside and local. For the IP use your IPv4.
Get your public IP Open a search engine (Google, DuckDuckGo) and search "what's my IP." Below the search bar should give you the results.
Change network properties: If you store your default port and IP in a constant or variable, change the IP to your public IP and the port to the one you just forwarded.
Hide your public IP: On FreeDNS register an account, and create a subdomain. You can name the domain anything you want, and use your public IP (use A-type). Change your game's default IP to the subdomain.