Alota glitches and losses

[ELITE COMBINE]

I play hl2dm every night and I somehow get my friends on there were we all play together but everytime we get to a second level of a sever it happens. We vote for a new level and like 7 minates after we all lose the conection and we end up back on the last level and have to wait again!. Has anyone else had this problem? The best thing to do is go find a sever with the level we want then we play there and when we move to next map and get kicked back we are still on the level we like.