ShadowResolutioin doesn't work on Android(Unity5.1.3)

I set 4 levels of quality exactly SAME except "Shadow Resolution", from "low" to "very high".
In Editor the effect shows below:
=============================================

==

==

==

================================

But on Android device, it looks like the shadow resolution doesn't apply with quality settings:

 

But on Android device, it looks like the shadow resolution doesn't apply correctly with quality settings:
==

==

==

==

 

So my problem is how to set shadow resolution to high/very high on Android device.
It seems the "medium" "high" "very high" resolution all have the same effect on this android device?
btw: the device is android os but not a mobile.
Thanks a lot!

 

This is often because the device has limited GPU memory to be able to create a shadow texture high enough, post what your device is so people can help. I can confirm it works fine on an S3 Edge (which is an awesome device), but not on a Mali 200 (Which is basically crap)

 

The device has 4G memory(shared by GPU and CPU).And I think the memory is large enough.However Unity engine can't get the GPU memory size correctly so the shadow map size can not be set to "high"/"very high".
I wonder is there any way to "force" the shadow map size to assigned?
Thanks a lot!

 

I know it sounds crazy, but memory is irrelevant to a certain extent, it depends on a few factors, first if it supports native shadows, which if it does then at what resolution, then if it doesn't what resolution of render texture does it support, and finally does it report it's memory correctly, if you have actually checked the value in SystemInfo.graphicsMemorySize and it's reporting incorrectly, I'd submit a repro bug stating the device, but it maybe a limitation of the device without knowing the exact device I couldn't say though.

I can say it works great for S6 and Nexus 7 (2013 model) as I've tested these, terrible for really low end devices, but that's to be expected.