If there are a majority of folks playing the server that dont have the new DLC, they could at least keep playing the server by voting for the old maps each time. But as it is, the server is filling and dumping like a roller coaster as old and new maps cycle.
There has to be a way to only kick non DLC folks once the map has been selected and has started loading, not in the lobby prior. As it is, non DLC players are kicked in the lobby before they can vote if a new map is one of the choices.
The already dwindling online community is getting split into those that have DLC and those that don't when most of us server owner are running old and new maps in rotation to try and cater to all players DLC or not.