Use application gateway IP can't not runserver

[redlightliu 1]

Hello
I'm under ddos attack, and attack method not Full bandwidth type.
I saw the flow very low, but my network still disconnect.

I used AZURE to set up Rathena.
AZURE Technical service staff help me set a application gateway to protection server.

Public IP  =>  GateWay  =>  My VM

Now had some problem.
   When I used this Public IP
   can't open rathena
   the login server is OK!  
   but the char server show error message "Connection to login server lost"
   and the  map server show error message "Connection to char server lost"

When I login server, I can see server total player. but cannot into char select

The error maybe in this 3 port they are can't connect each other?

And I tried to use My VM IP, can work.  (before I used this IP to set up rathena 2 month)
But not through GateWay, can't protection my server.

My settings:

1.char_athena.conf
login_ip: 23.105.111.102
login_port: 6890

char_ip: 23.105.111.102
char_port: 6145

2.map_athena.conf
char_ip: 23.105.111.102
char_port: 6145

map_ip: 23.105.111.102
map_port: 5278

Thank you!!!