To restore the auto-connect feature:
- From the Apple menu, choose System Preferences.
- Select the Network pane.
- From the "Show:" drop-down menu, choose "AirPort".
- Make sure the "By default, join:" pop-up menu is set to "Preferred networks." (If it was set to "Automatic networks", you can set it back to Automatic after the next step.)
- Select any network that shows WPA2 security and use the minus (-) button to remove those networks from the list.
- Once all WPA2 networks have been removed from the list, use the plus (+) button to add them back. (You will need the appropriate passwords for the wireless network.) If it's more convenient, you can wait to re-add the networks until you use them—when you use a network, it will be added to the list automatically.
- If in step 3, your default was Automatic rather than Preferred, go ahead and change your default back to Automatic.