The disconnection process differs between iOS 10 and iOS 9.
1. issue a connection request (Connection Request) from iOS.
2. the peripheral issues a Connection Request Indication.
3. Issue a disconnect process from the peripheral.
在iOS 9 will be identified as disconnected and disconnected immediately.
However, iOS 10 identifies it as timeout and takes time to disconnect.
Is this a problem with iOS?
Is it a problem on the peripheral side?
