I have a DJI Spark and remote controller using a USB Cable to connect to my Android phone (Moto x4/Android pie).   Initially this has worked flawlessly.   

Within the last week, I have had issue with the phone maintaining connection to the remote.   Rebooting the controller has seemed to help get connection back, but often it is only for a few seconds before the remote loses connection again.

Wondering if anyone else has had similar experience or if a software patch/update may have changed the behavior..

May try an alternate cable.

Thanks for any feedback on similar behavior or fixes.

Hi, we're sorry to know about that situation. Unfortunately, the mobile device that you've mentioned hasn't been tested by our engineers. Therefore, we could ensure the stability of the app while using it or the behavior may change if there will be an update within the application. We would recommend using a compatible device to prevent this type of situation. You may refer to the image below for our compatible devices. We do appreciate your understanding.

I have been having that same problem, i would like to know how to fix it as well

Please explain your DJI Go 4 version,  RC & AC firmware etc.  You only told us the Android device in use.  I have similar issues with the latest versions - thus downgrade the DJI Go app until it works.  DJI focus on the latest & forget about the rest that worked in the past. I can prove this is undue within their recent update policies.
Result: Don't buy a DJI Drone or be forced to jump when they say to jump. Simple, yet against the law & unfair in my country!

Downgrade the app till it works again, I'd say

I had this the other week, which caused a freeze up and spark to RTH.  

Fix I found was putting phone in to Aeroplane mode before plugging it in.  Now works fine.  

I'm wondering if phone still tries to connect via wifi even when plugged in via usb, so causes confusion??  Either way, now working for me

13rovers Posted at 3-25 00:00
I had this the other week, which caused a freeze up and spark to RTH.  

Fix I found was putting phone in to Aeroplane mode before plugging it in.  Now works fine.  

In case your wifi is ON,
(I'm wondering if phone still tries to connect via wifi even when plugged in via usb, so causes confusion?? )
in case the RC starts, and before you plug in the cable, there is a big chance, you are wifi connected, too.

Do you use an iphone? If so then you can actually use WiFi to connect to the remote.

S-e-ven Posted at 3-24 22:53
Downgrade the app till it works again, I'd say

where do I go to find the 4.3.12 which worked perfectly? Any ideas?

Maybe its Pie (Android 9) related?
Pie force some charging stuff on usb connections.
Pilots with disconnections, please provide details!

Haggi Posted at 4-8 08:48
Maybe its Pie (Android 9) related?
Pie force some charging stuff on usb connections.
Pilots with disconnections, please provide details!

I use an Samsung 9+ (Android 9) and lately since upgrading the DJI Go 4 the app will simply closedown mid flight.  Disconcerting but not difficult to recover.  Never used to happen with 4.3.12 which I would like to go back too if I could remember how!

Charliejspark Posted at 4-8 08:00
where do I go to find the 4.3.12 which worked perfectly? Any ideas?

https://www.apkmirror.com/apk/dji-technology-co-ltd/dji-go-4/dji-go-4-4-3-12-release/

S-e-ven Posted at 4-9 08:41
https://www.apkmirror.com/apk/dji-technology-co-ltd/dji-go-4/dji-go-4-4-3-12-release/

Thanks - would never have found it!

And, is it working like before?

S-e-ven Posted at 2019-4-9 08:41
https://www.apkmirror.com/apk/dji-technology-co-ltd/dji-go-4/dji-go-4-4-3-12-release/

HI Everyone..........

New Spark flyer here. I too am having the same problem with all of my Android devices.  

So far I've tried to no avail MULTIPLE known good cables, Pixel 4XL, Moto X4, Samsung tablet and today, will try an old S7.  Grrr.  In all cases, I've also first gone into airplane mode, previously set up developer options turning on usb debugging and data+power as the default usb connection type.  Nothing, nada!  

Via Wifi, connection established well within 30 seconds.

I think my only option is to downgrade the DJI App and try........ problem is, I don't know how to do...  I can get to the suggested apk page but after that.......... no idea.  Any suggestions?

You need to download the apk to your phone/s

After that, sync the original go4 and uninstall it
Tab on the downloaded apk, phone will tell "installing from unknown sources needs to be on, switch that on, install, test, fly