The cause of the downtime was poor coding practise from a wizard. Spanking will follow.
The MUD is down because the driver keeps crashing shortly after startup.
I have been unable to figure out what exactly is going on, since I'm
too busy at work to get enough continuous time for this problem. I'll
try to look into it this afternoon.
Update: Most of Oslo, actually. Good going.
Large parts of Oslo suffered from a nearly 40-minute long power outage between 17:21 and 17:59 UTC. Although we were on UPS, the server had to be powered down to avoid heat problems and overloading the UPS at 17:53. Our server was powered up again 18:09.
The server will be rebooted at 06:30 UTC for a kernel upgrade. Expected downtime is just a few minutes, but because the MUD starter script will be disabled from now until then, any crashes will result in a downtime until after 06:30.