Addition information from log: For first device: isBluetoothAvailable() scan() CentralManager( central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) (peripheral <CBPeripheral: 0x267hg5670, identifier = 98HG761CE-56C3-K767-26HJ-E51BA678Gh56, name = DeviceOne, state = disconnected) CentralManager( central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) scan() CentralManager( central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) (peripheral <CBPeripheral: 0x267hg5670, identifier = FJ1478HJ-EH8J-6709-1FH0-1456HGJ0BC901, name = SecondDevice, state = disconnected>) stopScan() connect(peripheral: CBPeripheral) (currentPeripheral nil, currentPeripheral nil) CentralManager( central: CBCentralManager, didConnect peripheral: CBPeripheral centralManager(:didConnect:) - didConnectPeripheral FJ1478HJ-EH8J-6709-1FH0-1456HGJ0BC901 Second device savedPeripheralString FJ1478HJ-EH8J-6709-1FH0-1456HGJ0BC901 Second device Bluetooth stop() currentPeripheral Optional(<CBPeripheral: 0x2jk875fe0, identifier = FJ1478HJ-EH8J-6709-1FH0-1456HGJ0BC901, name = SecondDevice, state = connected>) disableSleep() peripheral( peripheral: CBPeripheral, didDiscoverServices error: Error?) peripheral(:didDiscoverServices:) - didDiscoverServices for peripheral FJ1478HJ-EH8J-6709-1FH0-1456HGJ0BC901 peripheral(:didDiscoverServices:) - didDiscoverServices for peripheral.services Optional([<CBService: 0x2jkki2dc0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5>, <CBService: 0xhj67c240, isPrimary = YES, UUID = Device Information>]) [<CBService: 0x5678f2dc0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5>, <CBService: 0x28186c240, isPrimary = YES, UUID = Device Information>], peripheral.services is Optional([<CBService: 0xhjy62dc0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5>, <CBService: 0x2hju7240, isPrimary = YES, UUID = Device Information>])) service.uuid.uuidString is 59DE3994-6A63-4654-8FF0-F85C5163B2F5 and services is [<CBService: 0xhj7892dc0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5>, <CBService: 0xhjk678340, isPrimary = YES, UUID = Device Information>] peripheral(:didDiscoverServices:) - didDiscoverServices SecondDevice 59DE3994-6A63-4654-8FF0-F85C5163B2F5 peripheral(:didDiscoverServices:) - didDiscoverServices for peripheral not found FJ1478HJ-EH8J-6709-1FH0-1456HGJ0BC901 For second device: isBluetoothAvailable() scan() CentralManager( central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) (peripheral <CBPeripheral: 0xh6789a40, identifier = 98HG761CE-56C3-K767-26HJ-E51BA678Gh56, name = DeviceOne, state = disconnected) scan() CentralManager( central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) (peripheral <CBPeripheral: 0x678jhs0, identifier = H56KIL35-7835-7JKL-2B11-HJKLIYTAA400, name = ThirdDevice, state = disconnected) CentralManager( central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) stopScan() connect(peripheral: CBPeripheral) currentPeripheral nil, currentPeripheral nil CentralManager( central: CBCentralManager, didConnect peripheral: CBPeripheral centralManager(:didConnect:) - didConnectPeripheral H56KIL35-7835-7JKL-2B11-HJKLIYTAA400 savedPeripheralString H56KIL35-7835-7JKL-2B11-HJKLIYTAA400 Bluetooth stop() - currentPeripheral Optional(<CBPeripheral: 0x78jkl680, identifier = H56KIL35-7835-7JKL-2B11-HJKLIYTAA400, name = ThirdDevice, state = connected>) disableSleep() peripheral( peripheral: CBPeripheral, didDiscoverServices error: Error?) peripheral(:didDiscoverServices:) - didDiscoverServices for peripheral H56KIL35-7835-7JKL-2B11-HJKLIYTAA400 peripheral(:didDiscoverServices:) - didDiscoverServices for peripheral.services Optional([<CBService: 0xlki8901c0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5 - same like for secondDevice>, <CBService: 0x281111180, isPrimary = YES, UUID = Device Information>]) services is [<CBService: 0x2827444c0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5 - same like for secondDevice>, <CBService: 0x282744580, isPrimary = YES, UUID = Device Information>], peripheral.services is Optional([<CBService: 0xlki8901c0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5 - same like for secondDevice>, <CBService: 0x281111180, isPrimary = YES, UUID = Device Information>])) service.uuid.uuidString is 59DE3994-6A63-4654-8FF0-F85C5163B2F5 - same like for secondDeviceand services is [<CBService: 0x27893kdc0, isPrimary = YES, UUID = 59DE3994-6A63-4654-8FF0-F85C5163B2F5 - same like for secondDevice>, <CBService: 0x679kh8580, isPrimary = YES, UUID = Device Information>] peripheral(:didDiscoverServices:) - didDiscoverServices ThirdDevice 59DE3994-6A63-4654-8FF0-F85C5163B2F5 - same like for secondDevice peripheral(:didDiscoverServices:) - didDiscoverServices for peripheral not found H56KIL35-7835-7JKL-2B11-HJKLIYTAA400 Based on logs information in peripheral(_:didDiscoverServices:) - didDiscoverServices, app connected to my first service UUID and first characteristic UUID, that is wrong! Can not understand how this is possible. Thanks any help!

Thanks Quinn! It helped to fix my issue!