Michael thanks again for your answers. Hope i not too annoying you with this those nooby questions.

Such small fillet is not required, its better if rounded edge would have wider angle. It would be hard i guess to mimic that fillet result via Network operator.
I just want to understand the logic and rules that network use. I can't understand what exactly cause the problem with this shape.
- Is it a center spot that i used to divide edge profiles on equal parts.
- Or its an angle that i choose to divide profiles.
- Or maybe the different number of points in rail profiles.
- Or its maybe a sharp points in curves.
- ... etc.

I now know how to build rounded shapes like those that we build in Q_01.
But for more square like shapes that also have smooth edges and tilt (so they not easy to trim or extrude) i still don't know what to do.
The trim approach and extrude creates sharp corners and i need this shape as one piece(or 2 mirrored pieces).

The result shape on a picture is a combination of extrude, trim and loft. But if you look on it, shape lack of continuity and smoothness on edges.
That's why i want it in one piece. I know that for such shapes it would be easier to make it in polys and import to moi.
But i want to learn the cad approach and its limitations.