I upgraded my DJI mavic Pro in early Jan and was only successful after 3 attemps. I then flew it successfully. Once upgrading IOS 11.2.2 on my iphone 7plus. The Mavic will not connect to my DJI GO 4 app on the phone. It is permanently disconnected. I have deleted the app and reloaded it. It still does not work. I am so frustrated. I have tried every option. HELP