Connecting a Cisco 1841 Router to a Satellite connection

Hoping that someone can help me….The connectivity is as follow; the ISP provided its own VSAT modem which is connected to a Cisco 2500 Router using the Serial port. The LAN port was connected to a D-Link Router which is used as DHCP server.

When trying to connect the routers using the LAN port. We can ping IP address 4.2.2.2 on the outside, but cannot ping anything else. I tried using static IP addressing in the clients, and still does not work. What can be causing this strange behavior??

JB