Now, if we can all put our collective intelligence together and come up with a universal fix... unfortunately, the samsung products I'm using kill their own data connection whenever wifi is attached to anything, even when the connected whatever has no internet. Smart network switch is no help, in fact it hinders connection to the drone controller since it has no internet access to offer. Ughs.
That being said, I am having better luck getting my galaxy amp prime (V1) to behave finally. The original problem began when I tried to run GO4 on the same phone as Go (legacy). Before loading GO4, GO worked fine, unless I was trying to connect with strong interference.
MY fix appears to be the following: Completely uninstall both GO and GO4, making sure to delete any and all dji folders in the system (sd and device). Reboot device, and do a fresh install of GO. Run back through the setup process, making sure interference is minimal. Voila, perfect video feed out past 500m (~1640ft).
Another point worth noting: If you experience any messages about "low transmission/video quality", try a reboot on the controller (only) and give it a minute or so. Everything should reconnect and the controller link should be solid. This is what is working for me anyway, and i was just about ready to box my P3S AND Spark back up for return while the returning was good. Gonna have to keep em both now, and I'm absolutely loving the Spark btw!
Thanks to everyone who are working to make our lives easier, despite our choice to invest in DJI products! The hardware seems rock solid, the software however, well, *ahem*. Happy flying all!!!