on ipconfig.xml from gameserver/config file edit this line:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Put old contents of ExternalHostname here, used by default -->
<gameserver address="Your external ip"> (can be take ip from here
http://l2topzone.com/myip.html )
<!-- Localhost access -->
<define subnet="127.0.0.0/8" address="127.0.0.1" />
<!-- LAN's, put old contents of InternalHostname here -->
<define subnet="10.0.0.0/8" address="10.0.0.0" />
<define subnet="172.16.0.0/19" address="172.16.0.0" />
<define subnet="192.168.0.0/16" address="192.168.0.0" />
</gameserver>
In gameserver/config edit server.proprietes
GameserverHostname = Your external ip (can be take ip from here
http://l2topzone.com/myip.html )
good luck