I need help getting "DJI Go 4" to connect with my Phantom 4.

New Phantom 4 owner since January 1st and was using DJI Go app on a iPad mini and also a Samsung S6 with success on both and a total of 31 flights. Today I went to fly using the Samsung S6 and upon opening the "DJI Go" app I get a message instructing me to use the "DJI GO 4" app, the ship would not connect to the app, thus not usable. I downloaded the "DJI Go 4" app, cleared all apps running in the background, opened and signed into the DJI Go 4 app, restarted everything and the ship will not connect with this app either. I tried many different things, but to no avail. (Samsung S6)

I then grabbed the iPad and using the "DJI Go" app (no notification pop-up), started everything up and flew two flights and used up two batteries. (flawless)
Any suggestions appreciated.

DJI Go message

Did you install the latest update?

Did you use the GO4 APP with the IPad?

No, I was using the "DJI Go" app on the iPad.

I believe that everything is up to date, I had all firmware updated prior to t

Please try to change another USB cable and check the USB settings, make sure USB debug and MTP mode are enabled.
You can turn on remote and aircraft firstly then APP.
Just to clarify, you deleted DJI GO after installing DJI GO 4, right?

Thanks Natalia,
I will check USB settings and that is the order I use; remote, aircraft then app.
I did not delete the original DJI Go app though. I had cleared app defaults and stopped all apps running in the background before turning anything on. I will delete the DJI Go app and try this later when I get a chance.

I used different USB cables and placed the phone in MTP mode. I then started things in the in the normal manor: RC then the aircraft and the app last and it won't show the aircraft as connected within the app. I know the RC and the aircraft are connected because as soon as the aircraft powers up the indicator on the RC led changes from red to green.
The only thing I did not do was to enable USB debugging. It is my understanding that I would need to put my Samsung S6 into "Developer Mode" to accomplish this. (I wouldn't think that should be necessary to make an application work properly on my phone)

Also deleted the DJI GO app off the phone prior to trying the steps above.

I welcome any suggestions.