I'm assuming you are using windows. Join a game, then Alt+Tab, and open up run, and type in cmd. Once the command prompt is open, type "netstat -n", without quotations. Under the Foreign Address column, find a listing that ends with :4000. The number before this is your ip. The number you care about is the 4th one, or, for example, mine reads 63.240.202.37:4000. This means I am on server 37. Then you just keep joining games till you get the ip you want