Join a wireless network before login

Export the existing wifi setup
​netsh wlan export profile %SSIDName% folder=c:temp

XML files of the existing connections will be exported to c:temp. Find the one you want all users to access. You need to modify the to false and enter the wireless key.

You will end up with something like this:

<?xml version="1.0"?>
<WLANProfile xmlns="http://www.microsoft.com/networking/WLAN/profile/v1">
<name>Best Network</name>
<SSIDConfig>
<SSID>
<hex>42657374204E6574776F726B</hex>
<name>Best Network</name>
</SSID>
</SSIDConfig>
<connectionType>ESS</connectionType>
<connectionMode>auto</connectionMode>
<MSM>
<security>
<authEncryption>
<authentication>WPA2PSK</authentication>
<encryption>AES</encryption>
<useOneX>false</useOneX>
</authEncryption>
<sharedKey>  Click here for more details..

Contact Details:
Jaytag Computer Limited
Maddison House, 226 High Street
Croydon, Surrey, CR9 1DF
Phone: 08007879258
Web: https://www.jaytag.co.uk/