Then accept my sincere apologies for the final joke...
Confirm that I flew tenths of flight in very remote areas, without any phone signal and without any problem in controlling the drone via RC. Positive, you do not need it to control the bird.
Another story is if you do not see the map of the area where you are flying on the app: of course no phone signal, no data, then no map available under the lines drawn by the flying bird on your monitor, unless you have the area's maps cached in your app's device (phone, Ipad etc.)
But not connecting at all, no, never seen.
Still, Merry Xmas & Happy New Year !