Bluetooth doesn't stay connected after update 11.2 Updated to iOS 11.2 and now my bluetooth device (tune2air) only stays connected for approx 30 seconds before disconnecting. 

If I restart the phone, or tune2air device then it will reconnect but again only for 30 seconds. It will allow me to play music within that 30 second span.
Go into Settings > Bluetooth > MY DEVICES and tap on the Information icon ('I' in a circle) to the right of the device, then tap Forget This Device. Tap again on Forget Device (in red) to remove the device. Re-pair the device and see if it stays connected as expected. This has worked for me with other Bluetooth devices (I don't own a tune2air) that have developed intermittent connections.