The browser is probably picking up the private IP address of the iFolder server instead of the public IP address. To solve this problem, make sure that the public IP address is the one used in the ifolder_nav.html file in the sys:\apache\if older\documentroot\html directory. Then enter a static NAT that translates the public IP address to the private IP address, and make sure that the ports used for iFolder are not blocked at the firewall.