Tech support have said the phone same thing - roll back the firmware.Mine works solid but I know some mentioned on F series have an issue and you can go to previous firmware. Go to the Wifi screen and click on bottom right menu called Firmwares and click on 1.14 or 1.14.2 and update to that. That’s the original. I got this from an F series dude that had an issue and it fixed it for him.