When I make a dedicated server and I try to get on it with my account, when the game ends/runs out of time/someone wins, the server crashes and everyone gets kicked. I'm on DSL, does anyone know how to fix it? It's really annoying, I'd like to be able to play on my own server.

Did you check the "Loop" button above the maps? Otherwise, the game will end after the map list has been run through.
Also if your problem is something else you might wanna give the Soldat Console Dedicated Server on the Soldat.pl downloads section a shot. It runs as if it were another copy of Soldat.