Wifi dropping off with ios9.3 & 9.3.1

SInce the software update of iOS 9.3 and 9.3.1 the wifi on my iPhone 6 keeps dropping off. This happens in any house with wifi?! It's define story the software update always had full bars before. We have 3 other iPhones that haven't updated the software and this hasn't happened. I've reset wifi, reset my phone but nothing has changed. Desperate for help now