Servers

I notice something strange that has been happening more and more to me. I play typically on the US server, but sometimes when i join in fort, the server is nearly empty, with mostly bots and maybe 1 or 2 other players.

But when i go into queue for an arena or soccer match, the server is then full of active people (like 20 in one server), and then i can only stay for a limited time before i go into a match. Then i go back into fort and then it's full of bots and 1 person again. 

I don't know whats happening but i know that sometimes I can only go into a full server when i am in queue for a match, not on fort mode.