Hi. One of the reason of the low number of players on the server is the begining of a game. You have to wait for at least 15-20 player to make it playable. Thats means you have to wait for people to connect which is pretty long an annoying since we dont all have 1h to waste waiting doing nothing on the server.
So a suggestion would be to add bots on early to make the game a bit more attractive. I know bots are not really fun but at least it gives something to do when waiting player. Then bots disappear when more players connect.
I have no idea if its to do it on the server but imo that would helps to attract people on the server.