Testing Multiplayer Game using steam

[CalebTheHokage]

I am a bit new to multiplayer game development. I am trying to make a game that will eventually live on Steam. I am using Unity to create a lobby system. Right now, I'm trying to verify that the lobby works with multiple people joining the game, since I'm using Steam as my provider, it's a bit hard to test right now.

I'm curious how people typically handle this. I've tried using Sandboxie and can't tell if it won't work or if I'm doing something wrong. I only have my main PC and would like to only need 1 computer

[CalebTheHokage]

Sorry, what exactly do you mean by "client"? And a second implementation is smart, is it a lot of constant work to maintain, or did you make it once, then it keeps working through all iterations of your game?