RAK2171: Pairing failed

Hi everyone

I try to add a RAK2171 to the TTN. The app displays the DevEUI, AppEUI and AppKey as expected and when I try to set the frequency band to EU868 the message “Pairing failed, please rescan the device” appears. I tried with different RAK IDs on different android devices, but I cannot get the tracker running.

Is the app broken? Could anyone successfully configure a RAK2171 with the app?

Does anyone have an idea how to solve this?