What is wrong with my mesh(Blender)?

Question

3D

I was going to zasabdivaydit model.
But there's something wrong with the holes.
Like the chamfers were supposed to hold the subdivision. I can't figure out what the problem is. I would be grateful for any hint.

Answer 1

The chamfer is correct, but you forgot about quadrilaterals, quadrilaterals are normally subdivided.
here in this video about it clearly and briefly: https://www.youtube.com/watch?v=HTAj6vEciGg