I have an iPhone 6 on ios 9.3.1 which I've been using for a year without any issues. Two days ago whatsapp web started acting weird, it works perfectly while my phone is unlocked but a few seconds after i lock my screen the website says that the phone has disconnected. Then I unlock my phone, open whatsapp and instantly it connects. Any ideas? If i can't solve this i will have to buy another phone and i don't want to..