We have come across this recently where the iZettle card reader and the Socket Mobile are reporting as connected by Bluetooth but don't work
- Press the Home button on your iPad.
- Tap on the settings cogwheel icon.
- Select 'General'.
- Scroll down the general settings screen and tap on 'Reset'.
- Tap on the option to 'Reset Network Settings'.
After doing this you'll need to sign into your own local network again but your Bluetooth connections should be working again.