Samsung J7 2016 after 8.1 feels buttery smooth . Do a factory reset but with that also it so damn smooth better than nogut . Thanks Samsung for keeping the promise . No bugs . No lags yet and most probably wrong be there as well .
no Knox protection in device maintenance BUT check the software info. over there the Knox version changed from 2.8 to 3.2 ... don't worry even if knox active protection button is not showing . Samsung must have on it by default .plus you have S SECUR...