How to fix this broken smoothing groups

While modeling the nacelle of an airplane gun, after doing a boolean operation and after refining the resulting geometry, my smoothing groups broken down like shown in the image below. I have tried everything, even recreating the polygons hansn’t fix it. Same thing resetting the shade to flat and then to smooth again and also assigning a material. No way.

Someone knows how to fix the issue?
I am using Blender 2.93LTS

Have you tried recalculating the normals?

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Thank you very much! it fixes the problem :smiley: :smiley: :smiley: