If you install a wireless network adapter on a computer that has a wired LAN connection, the default gateway route for the wireless LAN may have a higher metric than the wired LAN default gateway, causing the wired LAN connection to be used first, because an adapter with a lower metric is always used if more than one adapter can be used to reach the same destination.
The default metric used on the first installed network adapter is 1. If two adapters in a computer connect to the same physical network, on the same subnet, the adapter with the lower metric is considered primary. The second adapter will only be used if the primary adapter fails, in which case traffic is automatically routed to the secondary adapter.
You can configure multiple default gateway addresses, setting the metric on each default gateway address. The default gateway with the lowest metric becomes the primary default gateway:
1. Open the Network and Dial-up Connections folder.
2. Right-click the Local Area Connection icon that you wish to change and press Properties.
3. Select the Internet Protocol and press Properties.
4. Press the Advanced button.
5. In the Interface metric box, type the new metric value.
6. To change the default gateway metric, select the Gateway address in the Default gateway area and press Edit. Type the new Metric value and press OK.
7. Press OK.