I have a custom framework that allows you to handle all Bluetooth actions, such as connect, scan, etc. Additionally, I have two applications using this framework: a test app and a real app. I'm trying to implement auto-reconnection for turning Bluetooth off/on and out of range. While it works well in my test app, it doesn't in the real app. Here is my logic: Firstly, I scan for a peripheral with a specific service UUID: manager.scanForPeripherals(withServices: [self.targetUuid], options: scanOptions) As a result, I have a CoreBluetooth callback response: func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) Then I connect to the peripheral: connect(cbPeripheral, options: options) And as a result: func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) After that, I save the UUID as a String. Then, I try to disconnect the peripheral from the phone (turn BT off/on or go out of range) and connect back. I've investigated different behaviours and found that in my test app, I have the same peripheral UUID even after disconnection, but in the real app, the UUID changes. I found this: The UUID will stay constant for a peripheral with randomized addresses for paired devices only for the lifetime of the pairing. If a device is not paired, according to the LE Privacy rules (RRA), the UUID will change as a peer unit is neither capable nor supposed to track a device across changing addresses. And this: Connection attempts do not time out (as stated in the Apple documentation: [link]). Just be sure to also keep a reference to the peripheral object; otherwise, the connection gets canceled. Here is my logic for reconnection in case of being out of range: centralManager(_:didDisconnectPeripheral:error:) [ERROR] - Peripheral was disconnected error -> Optional(Error Domain=CBErrorDomain Code=6 "The connection has timed out unexpectedly." UserInfo={NSLocalizedDescription=The connection has timed out unexpectedly.}) connect(cbPeripheral, options: options) My question is: What can affect UUID changing? Do I need to store a whole Peripheral Device object instead of UUID string?