Use your own group, don't use the sample group as you wil see some other people servers.
I guess you are already using your own group.
As long as the server part is running, you see the host in the list.
Normal, (188.8.131.52. and 184.108.40.206) only cache the data for a few minutes, and when not refreshed it's removed.
Auto flush take minutes, first both 220.127.116.11. and 18.104.22.168 need to flush it, then it need to be transmitted to the viewer.
You can press the refresh button (viewer site) to force a reload.
Are you sure they closed the server ? ( Try P2P connect, if it works it still running)