I have just received my first sonoff, and tested it quickly.
Rf433 works fine but I can not configure the wifi link.
I have installed the Android app and long click the sonoff button. I can even see the sonoff network name. But the app does not connect to my sonoff. It just shows a countdown and ends up with a timeout.
My smartphone is a Motorola X play with android 6.
I think these sonoffs are a little wonder. Please give some clues to help debugging this weird behaviour.