There are some peripheral devices such as the Suunto EON Steel which require the connecting BTLE central device to have a Generic Access and a Generic Attribute Profile. The device resets the connection as soon as it discovers the non-existence of the profile.

Most platforms such as Bluez and Android do generate those profiles for central and peripheral roles automatically. However since QLowEnergyController on BlueZ completely circumvents bluetoothd those two services are not created out of the box. While it is possible for Qt users to set those services up if the QLowEnergyController instance is running in peripheral mode, it is not possible to do the same in central mode.

There should be a way to setup those two profiles anyway.