OnePlus3 Android Shadow Issue

Hi,

I have an issue about the shadow in realtime on Android with my OnePlus 3.

When the camera is near the center of world position (0,0,0), all seems to work normally. But when the camera goes away from the center (example at a distance of 1000 meters), the shadow become pixelate & ugly. More the distance increase, more the quality of shadows decrease.

I did a test about the unity version : The issue starts with the unity 5.6. On previous version, I don't have issue on my mobile.

I also did a test on different mobile :

ISSUE on - One Plus 3 ( Android 7.1.1 )

WORKS on - Honor 6X ( Android 7.0) - Honor 8 (Android 7.0) - Samsung Galaxy TabPro (Android 5.0.2)

Screenshot from my OnePlus 3 with a distance of 0 meter from center https://ibb.co/eyVEo6

Screenshot from my OnePlus 3 with a distance of 1000 meter from center https://ibb.co/mC9kvm

Settings of quality & graphic (normally the default from unity) https://ibb.co/fag4o6 https://ibb.co/fskfT6 https://ibb.co/bsmXam

Have you any idea about this issue ? Perhaps is about the GPU of OnePlus3 ?

Thanks