Does not load any web pages when using internet through D-Link DIR-615 router

Does not load any web pages when using internet through D-Link DIR-615 router

I have a D-Link DIR 615 wi-fi router whenever I connect it to my internet
connection no web pages will load but i can login to the ISP's login page.
If I don't use the router and connect the Internet cable directly to my pc
lan card (D-Link | DFE-530TX+ 10/100 Fast Ethernet Desktop PCI Adapter) it
works flawlessly.
I am from India and my additional problem is that the ISP engineers are
not able to sort this problem for more than a month.
My ISP is http://www.dvois.com/
Any and all help will be appreciated. Thanking in advance.