You can play both on a local network and on a hamach:
1) Use the linked SF4Online.exe from the archive on both machines that want to play.
2) Enter the nickname in the window that appears, then click VS Action \ Add IP Address (and accordingly enter the ip of your “partner”)
3) wait while the connection is in progress, if the ip in the window is green – the connection is in progress, if it has already connected in red, so you just have to wait until it lets you into the game….
4) Start \ Versus Mode \ Player vs. Player (I definitely didn’t get to this point, but it seems that the one who enters the ip is 1p, and therefore it happens the same way as when playing on one machine, just at a greater distance =)))