Help needed with setup for internet connection on Dlink DIR 816

[Richard James]

Hi, I have purchased a new D-Link DIR 816 wireless router. I have a working modem and I am using Airtel broadband. I connected the router to my modem with the given ethernet cable and everything. I have done the setup but no matter what, the internet on my wireless router doesn't work. It is a dual band router. I have entered the correct username and password but I don't understand what am I doing wrong. Any help would be very appreciated please !!!