The upgrade moved us to a new physical machine thus changing our IP address, which is something that I did not consider. I talked to support and they are moving us back to another machine now but at the old location, which means we should be able to get our IP back.
Unfortunately it will take a while before this move is done (approx 2-3 hours). I am terribly sorry for the extended downtime and I invite everybody to join us for some discussions on the forums while the server is down. I will make it up to you guys (hint: item giveaway!)