I have the Phantom 3 Pro and had a problem with with video and data disconnecting about 20 seconds into my flight. I still had full control of the aircraft even though I lost video feed and data to my Ipad mini 4. The screen kept going black and said disconnected after about 20 seconds.
After several hours of reloading software on the aircraft and controller trying everything I can think of, my son comes into the house and says "hey Dad, I borrowed your cord to download some new music on my Itouch". I looked at the cord I'm using and realize it is not an original cord but a cheap one that was bought at Wal-mart.
I put on the original cord and now everything works as it should. I guess the cheap cord can not handle the data coming in from the controller after 20 seconds.

Thanks topleader for sharing your solution