Here is a weired thing happening. After some months of not using my drone I finaly pulled it out of the box and wanted to have fun. Unfortunatelly the Avata stopt after only a couple of meters and a message in the goggles appeared "aircraft not connected to dji fly". I never had to do it before but - why not try. I connected my phone with the otg cable, got the fly app running but the message in the goggles remained and the range was still limited. I turned everything off and on again - nothing changed !!!
Anybody an idea what to do with that? Everything seems to be working but the range is limited and the message persists.

It sucks big time.
Thanks for your input.

You need to connect the goggles to your device, then actually sign in to your DJI account from Fly on your phone.  

I had the same thing happen to me when I first got the Avata 2.  Make sure you have the latest version of the DJI Fly app as older versions wont work.  Log into your DJI account on the DJI Fly app, make sure that the Avata 2 and controller are also powered up.  You should see the FPV feed once you plug your phone into your Goggles 3.  It should work after that.

Hi there. Sorry about the trouble. Please refer to Dirty Bird's reply. To log in to the DJI Fly app, launch the DJI Fly app, go to Profile > Log In, and input the login credentials. Also please ensure your phone is connected to the internet when signing in. Please keep us posted. Thank you.

And it is solved. The app logged itself out of the account and this is not very obvious, neither in the app and certainly not in the goggle. I was able to see the feed from the goggle on my phone, which confused me. WHy not display a message which says - please log in to you account instead ???
Anyway, thanks for the tips!