You are most likely experiencing problems due to the highly detailed model and small edge size.
- I enlarged the model by 10x;
- I reworked the railing model, making the curves with fewer segments. I divided the created faces, creating quads, instead of a single face;
- I redid the railing surface, reducing it to 48 faces instead of the 376 faces of the one you created;
- You need to clean up the generated model. You probably need to improve the geometry of the railing model.
