Give this a try to see if it works:
- Press Windows key + A to open action center and click on All Settings.
- Now select Network and Internet.
- In the left panel, select Wi-Fi.
- Now in the right panel, select the option Change Adapter Options.
- The Change Adapter Options will open the Network Connections. You will find the network connection to which your computer or tablet is connected.
- Double click on the wireless connection to open the Wi-Fi status. Go to Wireless Properties.
- Under Connection tab, find out “Connect automatically when this network is in range“. By default it is enabled. To disable it, uncheck the option and tap ok.