"....when connected from modem to pc" Can you clarify that? Do you mean that your modem is still plugged into the PC?
Is this a modem/router - for use in lieu of a USB ADSL modem - or is it a router for use with a cable modem?
Tell us exactly how you have set up the router.
Is the ethernet LAN cable connected from the router to the PC when you try to access the config page? If it is not, then you won't get that config page because it cannot be accessed wirelessly - for obvious reasons really.