I have the same problem too

Try this procedure:

To Spoof a MAC Address

1. Connect the computer that your ISP's installers used to establish Internet connection to the router. If you are unsure which computer was used, call your ISP, and ask what MAC address was registered. Then, using the instructions in the box below find the computer whose MAC address matches their records.
   
2. Disconnect other computers from the router.
3. (If you do not want to disconnect other computers, you need to know the adapter's MAC address, as described in the box below. Then, in step 6, type Use This MAC Address, entering the adapter's address.)
   
4. In an Internet browser type the address 192.168.0.1.
5. Type admin for the username, password for the password, and click OK.
6. Go to the Basic Settings > Router Mac Address.
7. Select Use Computer MAC Address.
8. Click Apply. This automatically gives the router the computer's MAC address.
9. Click Test to make sure you are connected. If you are not connected, contact your ISP.