I have set it to clamp as wrap mode. i try different compression setting, but it doesn’t help. It always get this little white line on the edge of cube map. it doesn’t get this problem in editor, or android, or iPad pro. It only happens in my iPad Air 2. I have to try building it with Unity 5.3.6 and unity 5.4.1
I wrote a skybox shader to remove the line by adjust the uv