It hasn't been down, it's just been really backed up. For some reason, the IP "189.56.36.19" keeps popping up to be compared against the global ban list. It appears to be connecting to one of the Graffiti servers. The IP cannot be resolved, so it freezes up the login server for several seconds while it attempts to resolve it, causing other game packets to be dropped or severely delayed.
I've added some much-needed DNS caching (still needs some tweaking) which seems to have sped things up a lot. I'm not sure if this was some kind of deliberate act, or if it was just a deal where somebody left a client attempting to connect to a server with the auto-retry. It's rather strange that I can't find that IP in any of my logs. I would appreciate it if any GT admins could find any details on that IP and what might be happening.
In the meantime, the login server should be working OK now, but may go up and down as I make changes.