Trouble getting Bluetooth example working on Linux

Hi @all, 

I am not sure how to categorize my issue. I can not get the example btchat working on Linux (Ubuntu 20.04.1 LTS) . I can not connect to a HC-05 module connected to another computer via serial Interface. The Search wasn t providing any devices. So I had to do a minor modification to get at least available devices listed:

replace

m_discoveryAgent->start(QBluetoothServiceDiscoveryAgent::FullDiscovery)

with 

m_discoveryAgent->start().

I really do not know why this was needed. At least after that I get some devices listed.

After starting the program and pressing the connect button I get this warning below :

qt.bluetooth.bluez: Missing CAP_NET_ADMIN permission. Cannot determine whether a found address is of random or public type.

After double cliking on the device(HC05) I got this output in Application Output window:

Discovered service on "TRICORE-BT" "98:D3:71:F5:F8:1F"

   Service name: "Serial Port Profile"

   Description: ""

   Provider: ""

   L2CAP protocol service multiplexer: 0

   RFCOMM server channel: -1

And nothing else happens. Binding seems also not successful. please also note the -1 at RFCOMM server channel

To rule out that the example has a bug, I tried the same thing on a windows machine. There everything worked fine. RFCOMM server channel was set to one.
So the issue is related to my linux machine. What is missing on my machine ? Can you please help ?

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