Many Internet services do not want you to casually connect just any network device (computer or router) to their network. They will link your IP address, or network connection, to a specific MAC address entry in a database in their system, or in the memory of the modem connected to their network.
If you connect another device, with a different MAC address, to their network, they will deny service to the unknown device. Each different network device in the entire world, be it a modem, network card, or router, has a unique MAC address assigned when it is manufactured. Many broadband services will issue an IP address, and provide or deny service, based upon the MAC address.
If you connect a different computer, or a router, to your Internet service and get no connection, you will have several choices to force your service to accept the new computer or router.
Reset the Modem
If you're lucky, your modem is easily reprogrammed.
- Have all devices connected and powered up.
- Look carefully for a small hole on the back or bottom of the modem, labeled "Reset". Generally it will be large enough for just a large paper clip.
- Insert a straightened paper clip into the hole, and press ever so gently, maybe 1/32".
- Hold for 10 - 15 seconds.
- The lights on the modem will flash differently, indicating reset activity.
Reset the Broadband Service
If you can't reset the modem, you reset the ISPs equipment.
- Power everything down.
- Connect everything as you wish.
- Wait 5 - 10 minutes.
- Power only the modem on. Wait until the modem indicates service (the Line / Link / Service light is lit).
- Power the router on.
- Power the computer on.
If this procedure doesn't work, try again, but wait 1/2 hour or so. Some services reportably have a 4 hour retraining period, as the equipment behind the modem (at the broadband head-end) has to reset too. You may even have to involve your ISP, in extreme cases.
Change The MAC Address
If you can't reset the modem, or the service, you change the MAC address to match the computer that was previously connected to the service. Most network cards and routers will allow you to change their MAC address. This is called the Locally Administered Address, as opposed to the Universally Administered Address which is assigned at manufacture. The procedure for doing this, if available, will vary by vendor and by device.
Most network cards can be changed, in Windows NT systems, on the Network Adapter Settings wizard, which is accessible from the Connection Properties wizard. On the Advanced tab, in the Property window, you should find the Network Address. Change that to the appropriate value, and hit the Close button. Restart the system if necessary.
To find the MAC address for a network card, look in the output from "ipconfig /all".
Physical Address. . . . . . . . . : 00-04-76-D7-B7-6F
To change the MAC address of a router, you will probably use the router configuration web page. This process, called MAC address cloning or spoofing, will vary by router. You will have 2 possibilities here - either the router will allow you to manually change the MAC address of its WAN port (similar to the network card change above), or the router will automatically change its WAN port to match the MAC address of the computer that you are currently using to manage it (making the assumption that you are running the management program from the computer previously used for Internet access).
From the router configuration web page, find the MAC Address Clone (or Spoof) selection. Follow instructions - either type a MAC address, or select "Use this MAC address" (the address of the computer which you are on right now). The router will, most likely, restart, the modem will see a known and trusted MAC address, and will grant service.