I have been having conection issues with the remote controller and the aircraft for some time now.  The only way I was able to fly was to connect the controller to the Phantom 3 Professional via the provided cable and after a few minutes I was able to fly.  But the next time I would fly, I had the same connection issues with the aricraft and the controler.

Today I used page three of the firmware instalation guide which tells you to let the DJI GO app upgrade the RC Controller.  I was sceptical, but conected like the guide said and it told me my controller needed upgraded.  I had always thought the Phantom would update this when I loaded new firmware, but I was wrong! The DJI GO app upgraded my controller and when it was done I turned it off and started up the Phantom 3 Professional and the controller and it connected right up just like it should! I was overlooking the fact that the new RC version needed to be updated from the APP.  I have wasted a lot of time and effort and the instructions to solve the problem was right there in a PDF where I get the firmware.  Save your self some time and headaches and try this and see if it solves your problems.  There are so many threads in the forum about these problems, but this is what solved my problems.  Give it a try! I am just a neewbie to drones and sometimes it takes a while to learn things.  Good luck! ( IOS using an iPad air2)

Thank you for sharing your experience with us.
Hope you enjoy your flight.

Just goes to show, that a manual is worth reading.
RTFM

Good to hear everything worked out.