Pixel phones fail to disconnect

Question

We are experiencing a problem with our app, using nRF5_SDK_17.1.0_ddde560: 
 It works fine with Galaxy S20, but on Pixel phones (we tried 4, 6 and 7) it fails to disconnect. 
 In order to understand if the problem was due to our firmware or App, we tried with a Pixel 4 connected with the nRF52840 demo board running Peripheral UART demo (using the binary image downloaded from your site) and the nRF Toolbox (3.1.3) on a Pixel 4, replicating the problem. 
 Besides the Galxy S20 fails to connect to the Peripheral UART demo using nRF Toolbox. 
 Can you suggest any patch to fix the disconnect fail problem?

Aleksander Nowakowski · Answer

Hello, 
 I can add 2 things to what Hung said. 
 To get connected devices you have to open a GATT Server (the API is in BluetoothManager). You don't have to add any services. When opening a GATT Server you'll be providing a callback handler. One of the method there will be involved each time a new BLE device connected. It will also initially be called with existing connections. 
 The app to get connected devices may only with fire classic Bluetooth devices. 
 Another thing is about disconnecting. We never had issues with that on any of our phones, including Pixel. Remember that the physical link will be terminated only when the last BluetoothGatt object is disconnected. There may be multiple such objects connected to one device on one or more apps. 
 To make sure the device disconnects you would have to create an op code for that on the device side which you'd send to trigger disconnection from the phone.