I cannot access a certain Internet application or specific type of data applications?
Check the NAT page in the web user interface to make sure that the ALG supporting the Internet application is enabled. If the application requires UPnP IGD, check that “UPnP IGD” is enabled on the NAT page. UPnP IGD is used to provide automatic port forwarding allowing communication between certain Internet applications and the local network. When UPnP IGD is enabled, programs like MSN Messenger® and most network enabled games are allowed to pass the NAT service. A port forwarding rule might be required for a specific application. This is configured on the NAT page.