Server seens to be offline

Hi,

I'm using a bungee cord but from few days I have a problem with my server it seens to be offline but it is online. If there is over 200 players online no more players can connect to the server as it seens to be offline and players are not able to join the server.

Any one have any idea why this happens. I have been traying to update BungeeCord to latest version but it didn't help.