Subsurface modifier problems

Hey guys!

I’m kind of new on Blender and decided to use it to create a profile cut of a metal 3D printing nozzle. I did the cuts and the holes using the Bool Tool and now that I’m applying the subsurf modifier I have some weird defects appearing on both holes (top and bottom) as well as on some edges (right and left). I showed it drawing arrows w/ the grease pencil, but if it’s not clear enough I can send the mesh as well… Do you guys know how to solve this in order to have clean holes and edges? I know that it has something to do with the top & bottom faces but don’t know how to fix this… Here are the pics, thanks for your help!

Select all, mesh menu -> clean up -> split concave faces

There’s no such thing as subsurface modifier. It’s subdivision surface modifier. The modifier affects the surface, not something below it (subsurface).

This can also be done as curves and have the ability to change the resolution