Server keeps shutting down out of nowhere

When I play on my server with my friends, sometimes the server just kicks us and shuts down, and when I look to the Aternos page, I see nothing weird!

Can somebody please help me with this?

The only thing I found was:

[15:33:09] [Server thread/INFO]: Saving the game (this may take a moment!)

[15:33:10] [Server thread/INFO]: Saved the game

[15:34:12] [Server thread/WARN]: Can't keep up! Is the server overloaded? Running 35609ms or 712 ticks behind

[15:34:13] [Query Listener #1/WARN]: Unexpected exception, buggy JRE? (java.io.IOException: Operation not permitted (sendto failed))

[15:34:13] [Query Listener #1/WARN]: Unable to initialise query system on 0.0.0.0:10128 (Socket): Address already in use (Bind failed)

[15:34:13] [Query Listener #1/ERROR]: Failed to recover from buggy JRE, shutting down!