You use either tunngle or hamachi, a vpn program. Which stands for Virtual Private Network. They make it so that you basically have a lan sever through the actual internet, and as long as your friends are connected through the program to your private network they can join your lobby that you make in rfactor. If you using the dedicated.exe your own computer is using its resources to host the server, plus using the resources to try and run rfactor at the same time. So that is less resources (ram, graphics etc) that your computer has to make your rfactor experience better. I don't know how many times i had dropped fps running lfs with the dedicated file running at the same time. If you had a pretty powerful pc which i'm sure people do it wouldn't much of a bother. For people who don't have a powerful pc or a second pc they could run the server on this makes it easier as you can have your whole computers power to run rfactor at your maximum settings possible while still having a server since the server is ran on the vpns servers while not costing you a cent to host them, or it just bridges everyones internet networks together i'm not too sure which it is, but it works really good for small groups, maybe not if you wanted a huge server like driftbox.