Question about losing sessions

Issues with being in a session then everyone leaves, did the port forwarding thing, helped a bit.

Here is my question, lately I have been staying on the map and practicing flying, recently got a Buzzard so dialing that in.

HERE IS WHERE I AM LOST..... If i stay in the "room" long enough the session starts repopulating with players again

So, is it me that is logging off the session? or everyone else, since if I stay and people come back in, and can play as normal.

Im lost now as to what is actually happening