Information
Enabling Wi-Fi Auto-Join for a Wi-Fi network configures the device to remember the network and login information and automatically reconnect to that Wi-Fi network whenever the device is in range. It is recommended that Wi-Fi Auto-Join be turned off for all network connections where security is paramount.
Solution
On the iOS device,
1. Tap Settings.
2. Tap Wi-Fi.
3. From the Choose a Network list, locate the network SSID and tap the Detail Disclosure button next to the network to change.
4. Turn off Auto-Join (see note below).
5. Repeat steps 3 and 4 for each network SSID.
Note: This feature is primarily applicable to the automatic joining of subscription Wi-Fi networks. Wi-Fi must be turned on and the Wi-Fi network must be in range for it to appear in the list of available networks to configure. The Wi-Fi network must require network login credentials and must be remembered or currently connected for the Auto-Join option to be present.