If your WiFi network is hidden:
From the Admin Options screen (swiping left to right on home screen, hitting settings, and entering the 07139 PIN), select "Wi-Fi Settings."
Scroll to the bottom where an option of "Saved Networks" will appear
Select Saved Networks, then click "+ Add Network."
Enter your Network Name, select "WPA/WPA2 PSK" as the Security setting, and then select "Advanced Options."
In Advanced Options, the last field will read "Hidden Network."
Select "Yes" for Hidden Network, then Save. This will allow the Hidden WiFi network to show as a connection option for your terminal.