What happens yo the Minecraft server?

Hello Aternos I have a problem that never happened to me. I tell you I was playing with friends in the forge 34.1.0 (recommended version) (1.16.3). We had been playing for a while when suddenly the world does NOT drop the objects, it takes us off the server but says that there are people inside, if you try to enter it puts you: timeout. But the strangest thing is that on the atomic page it says that there are people playing and it won't let me kick the players that the server thinks we're still inside, the only thing I can do is turn it off or restart it. What happens? If I have not explained it well somewhere, ask me and I will explain it better. One thing the world does not crash or anything if I leave it open, it is as if there were someone and it does not close but there is no one