Uploaded your flight log to Healthy Drones....HD is not perfect, but good enough for general info.
It indicates a couple things. You had very poor data signal almost the entire flight. About half way thru your flight, you lost data signal for over a minute and it initiated RTH. It appears the signal returned and you continued flying. At about 15 minutes in, it indicates critical low power and initiated auto land.
In addition, HD indicates your altitude at 1,606' and distance to home point of 1,800'+.
Meta4 is spot on. The Phantom preformed perfectly. It appears it calculated it needed to land based on the altitude and remaining battery level. It took over 2 1/2 minutes to descend 1,500'
Good to know that it was flying as it should. I appreciate you taking a look. I think what through me off on my judgement of when to come home was the altitude. Normally when I fly at a couple hundred feet, 30% battery is when I start to come home.