/members/frns4life/ Your PM.
1.If you cannot access the Virtual server page, nothing more can be done.
(similar problem in my modem also for DDNS page )
2.You had earlier reported , I think , that in telnet also you were stuck in "6" NAT.
( confirmed by senior contributer@superprash2003

Post 63. also in his modem. there are two types )
3.Stay with DMZ option for the present.
4. Only way out , ask BSNLto replace the modem, if modem on rent.
5. Or try for firmware update, at your own risk. ( see Para two)
6. If modem becomes "dud" Don't blame me.
7. BSNL may give a replacement for a working modem (either for rented or purchased within a year )
Try your luck.
Para two : give the link of Device Status.of your modem.