Cylindrical forms are impossible to bake in low poly shells perfectly well. There always be some trade offBut in your case you could add support loops for baking and then remove them ps. Actually in your case you could just make seamless unwrap ( with a single seam) and do geometry bevels being all a single smooth group +…
For low res model in places where it supposed to be flat 128,128,255 normal color. You could delete those loops after bake . It makes sense it you have split UV unwrap and hard edges. I would still try to make chamfers, face weighted normals and tube like unwrap. Hard/split edge with UV split or chamfer without UV split is…