Set LAN to take network priority before Wi-Fi on Windows 7

To make the wired LAN connection take priority you need to change the metric for the WIFI connection in the advanced settings pane of the WIFI connections' properties.

Untick the 'Automatic metric' and set the metric to 9999 manually

Next open a commandline with admin rights and submit this command to clear the routing tables:

route /f

After this step reboot windows to make sure the new metric value gets used.

Upon rebooting the routing tables will be rebuilt using ARP-discovery, causing the new metrics to be assigned to the routes. The net effect will be that to your TCP/IP stack it will look as if hosts/devices connected to the wired LAN have a more efficient route than those connecting via WIFI only.

https://support.microsoft.com/en-us/kb/299540