Website won’t display after changing ISP

After changing ISP & Router, I can view any website I want except my own which is hosted and viewable outside my location. On all PC’s at my LAN, IE displays only Index of: and a list of parent and subdirectories. IE gives a “Page can’t be displayed” if I add /index.html to the URL Have deleted cookies & files in IE, but not History. Router has NAT but Firewall is open for port 80. Help!