Dedicated Serwer bug

Hi i just have done my ded. serwer and works great but when someone connect to serwer and disconnect and connect again serwer crashed writres " Buffer overflow in net message" like this in console serwer.

1.Connection too slow.
2.Running connection-intense programs in backround.

I’d be good if you wrote your connection speed.
also, it’s server not serwer.