since I have the OnePlus 6 with Android 9 I can't really use the tello.  I can't do a software update, its every time on 0%, I have to reconnect  to the WLAN every connect and check the "yes", that the tello has no  internet and after 20 second of flight the app crashs. why?! I  googled and read in the OneplUs forum, that the 6 is not compatible?? how can that be??

Hey, Max，sorry for the inconvenience caused. In regard to firmware upgrade issue, can you try the method below?

Step 1: Power off the drone first.
Step 2: Hold the power button for about 5 to 8S until the green led goes off
Step 3:  Once succeeded, the drone would flashing red led.
Step 4:  Find a wifi called "" Tello - xxxxxx"", then connect it.
Step 5:  Launch into Tello APP and redo firmware upgrade.