If you have both a wired cable connection and a wireless network configured as active on your Computer, with both using the same network Gateway address, e.g. your ISP router IP address, then Windows will auto prioritise network traffic based on the speed of connection via auto assigning each a 'Metric' value.
When more than one network connection is available, Windows uses the one with the lowest metric value. For further explanation of the Automatic Metric feature for Internet Protocol routes see:-
https://support.microsoft.com/en-us/kb/299540
If you feel it necessary to force Windows to use a specific network connection, then assign a metric value to each one (giving the lowest value to the desired connection), setting as follows:-
- Right-Click the Wireless Icon
- Select 'Open Network and Sharing Centre'
- Select 'Change adapter settings' (listed on lefthand side of Window
- Right click the desired connection.
- Click Properties > Internet Protocol Version 4 (TCP/IPv4).
- Click Properties > Advanced.
- Uncheck "Automatic metric".
- Enter a number between 1 and 9999 for the "Interface metric" (lowest being the priority)
- Click 'OK'