If you want to prevent your iOS device from automatically connecting to a network, you can ignore this again..
Every time you reconnect to a WiFi network and the associated password, your iPhone or iPad saves this network. As soon as you are within range of the WLAN again, your device will automatically connect to it. If you do not want your device to automatically connect to the network or if you have a problem with the connection, you can ignore the WLAN including password. If you want to use the network again, simply log in again with the WiFi key.
Follow our step-by-step instructions or take a look at the brief instructions .
Tip: More tips for problems with iPhone WiFi can be found here..