Further to my earlier post #98...
Rolled back from latest DJI GO update 4.1.3 where i most certainly AM getting video lag problems and sometimes 'CPU error' problems on an iphone 6, to DJI Go 4.0.7. This update was from April this year where I definitely was NOT having any issues. I didn't touch the .0900 firmware.
Went for a fly, and the video lag problem seemed to be improved. However, it would not let me fly over 30m. I logged out and logged back in to the DJI website, with no avail.
Clearly the flying restrictions introduced on the .0800 firmware don't talk properly to anything prior to DJI Go 4.1.0. So I thought - fine, I'll roll back the firmware too.
4.0.7 DJi Go matches with .0600 firmware, so I thought I'd just roll back to .0600 using DJI Assistant.
So I go online just now and see that DJI has removed all previous firmware except for .0800 and .0900.
So I'm totally screwed.
1. DJI Go 4.0.7 should resolve the video transmission lag issue, but I now can't access the firmware that went with it. Current firmware prevents me flying over 30m no matter what.
2. DJI Go 4.1.3 allows me to fly with 0.0900, but still has the lag issue.
Guess I'll just go back to 4.1.3, put up with lag, and hate the world.
BTW, if you are testing whether or not you have the lag issue, please test using active track, as I have found it most problematic there.