This happened with my P3P. I did the latest firmware upgrade and it cut my range in half. This was because of the affect it has on the drones ability to send and receive signals, not the controller. So I try to avoid updating my firmware unless it's absolutely necessary. My experience has been that changing the firmware on the controller has little effect if any on the range. Supposedly you can downgrade the firmware on the controller. On the DJI Go App screen where you push the blue camera button you will see a little hat in the upper right corner. Hold this for 10 seconds and you will see a screen pop up that allows your to down grade the controller. Sometimes this works. Most of the time when you do the downgrade and the controller will still show the latest software. I haven't found a way to downgrade the drone.
