I write review on Samsung Galaxy j7duo .totally worst phone.in there same problem the phone was so hang when you use internet .or many file .when you buy that phone .new phone working good after 1 or 2 month the phone was so lagging .you can't play any big game on this phone . Camera quality is not good. you can't open many file on this phone it was hang .so we can't do any thing on that phone so .I will say to Samsung team please improve your phone quality .why your mobile was so hang.thanks