Quick Multiplayer Question for external connections

Hello :)

So I've been trying to implement networking for my game, and so far I've successfully manged to implement the server hosting on the basic level.

Network.InitializeServer(numberOfPlayers, connectPort, useNAT); to host

Network.Connect(connectIP, connectPort); to connect

But what happens is that i cant connect to the server from non-LAN environment.

My question is: What should I be looking into next? Setting up my own Master Server? I do not want to use other resources. I want to be able to solely run the game off a clients computer and not having to use any external help/servers/proxies/VPNs. What should I look into to get started?

(For the most common question, yes I know how to port-forward, ports are forwarded and nat is set to true, my friend cant connect to my game instance from his PC)

Thanks!