This indicates that the UPnP server needs to be restarted. It seems to think that your BL server is already running on that port and so it won't let anything else use the port.
That's weird, because it posted to the master server fine, it said in the dedicated server window that is was running, and if I went into the game itself and hosted a nondedicated server, it worked perfectly well.
I'll try it again with an ethernet cord, and if it works, I'll post the server console again in case it shows a solution and how to fix it in the future.
If it doesn't work, I guess I'll have to reset it in the middle of the night or something.