It isn't a site as such, it is the address of the modem on the LAN side.
Out of curiosity, go to:
Start > Control Panel > Network Connections
Right Click on your connection and click 'Status'.
In the window that appears click the 'Support' tab.
It will have something like:
Address Type: Assigned by DHCP
IP Address: 192.168.100.2
Or at least something similar.
This is to make sure you were trying the right IP address to connect to it.