how to get correct shadow from the model

Hey, guys,

I created a model by Blender, and when I dragged it to Unity, I found that the shadow is not starting from the edge, looks like there is a gap or a leak so that the light can go through. Pls see below picture:

I know that to adjust the Bias and the Normal Bias close to zero value can make the shadow look correctly, but meanwhile the surface looks like some scratches. Pls see below picture:

Please, is there any suggestion that how I can adjust the model in Unity or Blender to get a correct shadow?

You have to increase the shadow resolution in the Light component or in the Quality Settings.