Some of my members had the same issue and our server is also located in Atlanta. (ts55.gameservers.com:9142)
Suddenly, they all can connect tonight after several days.

Having hosted that on a dedicated server in the past, I can tell you that it is extremely CPU-intensive even at 0 players. I had a dual-core system and 1 core always stayed pegged at 100%. We had to drop the game as it was affecting the performance of other games on the server. That being said, that...

The dedicated server files were released today. However, there seems to be an issue with running multiple instances on one server as the game only binds to the primary IP address of the server. I am hearing that there will be a hotfix needed to remedy this.