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I'm using a Windows 7 with wireless & cable equipments to connect to internet, it's been fine for months. But Three days ago, the local connection ran out of control and I can no longer use the cable to get access to internet. But fortunately the wireless equipment still works. I reinstalled the driver, took off/inserted in the cable, the computer still didn't work.

And every time I let the computer diagnose itself, it told me that:

Default gateway is not valid

(or something else, forgive my terrible English). If anyone could give any advice, I will be very appreciated. And I'm in California, but I don't know the gateway of this area.

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I am rather confused by "the local connection ran out of control".

I would check the cable for any physical damage and make sure there is a light on the computer and/or the router to make sure that there is a physical connection (although, even if there is, it doesn't mean it is 100% working).

I would also say it may be worth trying to restart the router in case there is a random problem there - obviously DHCP is working (If you are using it) as wireless is getting a good address.

Next, take a look at your wireless devices IP settings and possibly write them down, then manually place them on your wired connections settings. (either change the last digit of the IP to something not used, or disconnect wireless). This should take care if there is a DHCP related problem on Wireless.

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As Wil states, it could be the cable. Try swapping it for a different one.

Before I would try that, however, I'd try swapping the port used on the router.

Is your cable connected to the router directly, or via a switch? That's another potential point of failure.

If all previous suggestions do not help, perhaps you can find another NIC to try in your system (assuming it's a desktop)?

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