Login packet

Hi, first i want to apologize for my bad english.
So.. I have private server on VPS... there and play maybe 100 people but sometimes when somebody want to login it write: you will be connected to the server ..it type all time.
I think that someone sends packets on the login...
But auth core is ON(enable)
can anyone help me?
thanks

a server on virtual machine cant get Attacked by DDoS, so i think the auth server port going down..