回复：网络怪事请教

According to my experience, it is because your NIC MAC address was changed due to replacement of your primary computer's mother board. You must use this computer to setup high speed internet connection with your local cable company. Your local cable company would register your computer's NIC MAC address to identify your internet subscription. You are getting "limited or no connectivity" becuase yoru local cable company can't recognize your new NIC MAC address. You have to contact your cable provider to resolve this issue.

Hope it helps and let us know.

Bergen.