MP Hosting problem!!!

[Ataros]

Try flying online for an hour or more, see if you get the same error.

I assume you are not shutting down Steam after launching server. Try checking your connection to Steam maybe your provider looses some packets on the way to/from Steam or not all ports are open. Steam FAQ lists all necessary ports. If your provider put you behind a router you can host only in Lobby, not in Server room.