title: Can not connect to BLE device on raspberry pi (gatttool/bluetoothctl)
body: <p>like the title says, i am not able to connect to a le device on my raspberry pi 3. 
  I tried:
  - via bluetoothctl i get an AutenthicationFailure 
  - via gatttool i get connection refused (111)</p>
  
  <p>I searched a lot for a solution and already tried (made sure that):
  - btmgmt le up
  - reinstalling bluez/bluez to the newest version
  - use of "-t random" when using gatttool</p>
  
  <p>And know i really have no idea what to do next.</p>
  
  <p>What might be important:
  uname -r =  4.19.58-v7+
  bluetoothctl -v = 5.50
  Using the Android App nRF Connect the connection to the le device works fine.</p>
  
  <p>Can somebody help me please?</p>
  
  <p>Thanks in advance,
  Magda </p>