Thank you for your answer
@chatikib
OK. Yesterday I downgraded my DJI App (.18) with Fake GPS trick. Today I flew for 5 minutes AND it has f*** worked. Even with an Android Tab ! Such perfect : over 600m and still no problem to flight (last time was ~250m). I'll try one more time today and I'll do a feedback, but it sounds really good.
Weather situation : cloud/fog - 1,5° C - alt ~430m
Firmware DJI : last
DJI GO : .18
Mobile device : Android Galaxy Tab A 2016
I'll keep you informed.
EDIT : I forgot to mention that my remote antenna was on the opposite of my UAV xD ! That means, it would be even better if it was on the correct side !