1) get the MAC address of your PC adaptor using run->ipconfig /all
it will be seen as Physical Address. . . . . . . . . : xx-yy-zz-aa-bb
2) wire the pc to the router (any LAN port) and log into the config page
3) find the tab that contains the masquerade option [x] enable it and place the MAC address
of your system there
saved the settings and restart the router (power off; wait 30 sec, then power on)
Many ISP use Hardware Provisioning and the above is how we do it.
a) if your ISP doesn't, no harm
b) if it does, then this is the ONLY way you will get access to their DHCP configuration