Today I seen couple of nasty bugs related to network disconnection at iPhone - 1) Microphone button inside of exercise become frozen e.g. non clickable, unfortunately, where are no option to disable microphone just for that exercise 2) At the end of lesson I got pop up "Cannot connect to Duolingo", when I finished lesson, application shows all usual congratulations, moved to next lesson, after several seconds ( probably network reconnect ), it deducted reward for that lesson, locked out next lesson and rolled back to previous lesson.