The servers are on a rotation so the map comes up about once or twice a day.

=TaT= servers offer many custom maps and they are well populated.

=TaT= servers #2 & #3 currently supply nearly all of the customs. But they are vote servers, and so this will influence how often the maps come up. If you want to install the maps without depending on the servers, youi can download them directly from the developers thread at the Tripwire forums.

http://www.gametracker.com/search/ro2/?sort=c_numplayers&order=DESC&searchipp=50#search
open the console an type open [insert the server ip]
currently 20:30 GMT+1 there are 11 full server an a bunch of 3/4, 1/2