Update the firmware - Download here  Link-1          Intranet Link

List of things-to-do that will hopefully help you update it without any hassles.
0. Check your firmware version by looking at System Info on admin interface of the router.

1. Get the firmware from D-link India site or download from above link.
2.Warning: Dont update with wrong version
3. Download the .IMG file through anyone of the link provided .

4. Now, connect your laptop physically to the router using a RJ-45 network - the regular Ethernet cable.
5. Disconnect wi-fi access of the router or disable wi-fi temporarily.
6. Browse to the Admin User Interface of the router by browsing the management IP - typically 192.168.1.1 and give your user name and password as "admin"
7. Go to Maintenance menu>Firmware update on the left and then click on "Browse".
8. Select the file from the Computer folder using the browse button.
9. Click on "update firmware",(dont double click) if you have pressed it correctly, you will get a message "Upgrade in progress - please wait for a minute -Will reboot automatically"
10. Don't do anything else!
11. WAIT.

12. Don't do anything - WAIT.
13. Keep waiting - if you observe your router, the buttons will flash at some point and indicate that it is restarting.
14. Subsequently, your page should refresh and the home page of the management interface should reload.
15. If everything went well - your system should show System version as 1.00.07
16, Use your newly upgraded modem/router!
17.Remember: Disable WPS in advanced menu, Disable UPNP
18.Now the modem will not be pingable from internet. All open ports were closed

Happy upgrading!              Dlink 2750U Version - i1 Firmware link-1    link-II