My host has informed me that they need to reboot the server the game is hosted on to apply a security update. It is scheduled for:
Friday, 2016-07-22 15:00:00 UTC
Which is:
Friday, 2016-07-22 11:00:00 EDT (server time)
The game will be unavailable during the maintenance. Unfortunately this is around the time of the day when there are typically the most number of bots online - while there is a 2 hour window allocated, the actual downtime may be much less.