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Connecting to a Cable Modem with a Router (e.g. Virgin Media with the Linksys WRT54GR Router)
If a computer was connected directly to the internet without the router, then it is possible that you may not get a connection. The MAC address of the computer has to be cloned when connecting through a router. The cable modem should be power cycled when changing connected devices so it can learn the new MAC address. Depending on the limits, cable modems allow 2 or 3 different computers to be connected one at a time within a few hours.
If you insert a NAT router between your PC and the cable modem, you might want to avoid changing the client MAC address that the cable modem connects to, for either of these reasons:
to avoid having to register a new client MAC address with your ISP (if your ISP is one which requires registration of the MAC address of the connected device);
to avoid problems with the ISP's DHCP system not immediately issuing a new IP lease when the client MAC address changes (see Swapping computers on the cable modem).
Cloning the MAC address in the router makes the cable modem think it is still communicating with the same Network card as before, so you don't have to power cycle the modem.
Disconnect the modem from the router first, and connect the PC to the port one of the router then restart it. (This PC should be the one that can get online if directly connected to the modem)
Go to your desktop and double click on Internet Browser.
When browser opens, type 192.168.1.1 (or whatever the IP address for the router configuartion page is) into the "Address" bar and click on Go.
The log-in window will appear.
Type in the admin user name and password for that router (For a Linksys: skip user name and type admin - default password), and click OK.
On the Setup page, please make sure that the Internet Connection Type is set to Automatic Configuration DHCP or Obtain an IP automatically, then hit on Save Settings below.
Under the Setup tab, click on the MAC Address Clone sub tab and click on "Clone your PC's MAC" button, then save the settings.
Please go back to Basic Setup, then change or make sure the LAN IP address is set to your routers default IP address (such as 192.168.1.1 for a Linksys Router), and then hit on Save Settings below. Don’t worry if the page will hang or lock up.
Shut down everything for 2 minutes.
Connect the modem to the Internet port of the router and power on. (Starting from the modem then the router and lastly your PC).
With the cloned MAC address in the router's WAN port, then as far as the cable modem is concerned, it is talking to the original PC.
