My Custom games stop displaying after a while

I have now set up about 30 odd custom games and I’m having a HUGE problem.

After I set up a game, people join and it might get to half way through the game, with people leaving and joining over and over but at one point NO-ONE will join, till the end of the game, which could potentially last an hour or more. This leads to uneven teams and then they leave in a cycle.

I asked my friends to test this and after a while my games no longer appear in the custom browser, which is why people are not joining.

Why is it doing this, my connection is stable and I have no other problems?