Hi.
Few years ago I bought P3ST which was working from the beginning all the time, every time, with my Samsung S4, and Chinese made tablet with GPS, then Samsung S5.
Connecting with WIFI. Never problem.
Few months ago I lost my drone, 120m above, I lost connection because my new Galaxy Tab power went down to below 10%. Screen went dark on sunny beach, and I couldn't see anything. Most likely WIFI went off also. Instead of looking where is a drone and take him down with controller, I get panic and I change a switch for RTH, but most likely that was wrong switch, and instead a RTH, I changed mode to altitude. Mean time  I still tried to fixed my tablet, without looking where is a drone, and where is landing. After 30min+ drone gone and I left to hotel to change my tablet. 2h later I came back searching for signal, but no luck. Next day I walk through shallow lake for hours, still no drone, most likely a wing pushed him towards deep/rich forest. So I checked Flight record (first time in my live), but there was no flight record. On every location I had only one flight record, but when I changed battery, there is no second, third, or forth record.
Why it is not recording when I change a battery?
Drone gone 500km away from my home. Can't look for it any more.
So I bought P3Pro. Disaster!!!
P3ST had WIFI connection, never problem.
P3Pro has USB, and that's the problem. When you look on a P3Pro forum posts (16264 posts) you will find it is a largest forum mostly about connection problem.
I tried to connect Samsung S4 OK. S5 OK. But the Galaxy Tab is not recognizing controller/drone. Why? Because P3Pro has been designed to work on older USB settings.
I have read lot's of post about this 16264 total. All same problem, connection. The only one thing works on Galaxy Tab, go to Developer mode, and change a USB settings.
Sometimes it works after single change, sometime after 3,4,5,6,7,8,9,10 times. Change a setting, closing App, change a setting again, close the App, disconnect a USB cable, connect again, change a setting again, and again to MIDI, Ethernet, Audio, MTP, PTP, Charging, till I get connected. This is a pain in the aswell. I have a 4 batteries, and I have to do this every time.
Settings on my S4 or 5 are same as on a Galaxy Tab, but Tab has a newer software version and that's a problem.
On a internet I have read lot's of help about USB connection. In recent years companies change the way how equipment is connecting through USB.
Before when you connect phone, camera, GPS, or other equipment to the computer, both computer and equipment asked "Do you want to connect to the computer". On both you have to click YES.
So they change a system, cause some kind of problems, and Computer, Tab, Phone is connecting to recognize  an equipment, and is choosing automatically best connection for a device. But some Galaxy Tab, Samsung S7, S8, S9 has something new, and does not recognize P3Pro USB. So this is for me only: new equipment like Galaxy Tab, Samsung S7, S8, S9 has something new, modes, or settings, and DJI is not moving forward with new settings.
This forum is a largest, and still no permanent solution.
Years ago was better. One Audio and Video cable and you connect everything.
Now they making hundreds or thousand of different connections/equipment, and one to another is not compatible, because.
One is moving forward to fast and another is left behind and is moving forward with a snail speed.
DJI.
Do something good for us.
You can make a number one drone, but you can't fix simple connection. I now you can.
Thank you.

I'm sorry to read your post. For the connection issue of the Galaxy Tab, it looks like the compatibility issue. I‘m afraid that the stability cannot be ensured for the mobile devices has not been tested. Could you be more specific about the issue on Samsung S7 and S8 series? We will appreciate if you can upload some short videos for better assistance.

At a moment I have a problem with Galaxy tab T813.
I mention Samsung S7 and S8 only as lots of people with these phones have same connection problem.
I understand P3 has been developed years ago, and was working on our older phones and tablets. Now people have new phones, some want to use bigger screen (tablets). This is not DJI fault, we upgrading our phones, but only DJI can do something about it.
At a moment I don't have other option, only leave with this problem, and wait till new software updates will be available for my drone.
Thank you.

bzykac 2 Posted at 2018-4-10 17:31
At a moment I have a problem with Galaxy tab T813.
I mention Samsung S7 and S8 only as lots of people with these phones have same connection problem.
I understand P3 has been developed years ago, and was working on our older phones and tablets. Now people have new phones, some want to use bigger screen (tablets). This is not DJI fault, we upgrading our phones, but only DJI can do something about it.

The problem is not with the connection, it is simply a USB connection, and for the vast majority of people it works just fine. The problem is that DJI keep adding features and such to the DJO Go App, and older phones and tablets are not able to handle it well. In fact, it is more a problem fort Android based devices, the Apple products seem to deal with it much better. Your only option may be to get a newer phone or tablet.