What is the most practical way to test Multiplayer Online Connectivity between Clients?

Once all server/client programming is in and LAN multiplayer is working correctly, what is the best way to test connecting a Client to a Server Client over the internet? Do I necessarily need a second internet connection and computer or is there a work around to that? I am gauging whether I will be needing to invest in a second computer and second modem.


A second computer is the most practical, but if you just need some flavor for lag and package dropping, check here Finding Network-based Exploits - Unreal Engine