(Dynamic) Lighting Issues on narrow corridors/edges. (normal smoothing)

Hi, I have quite an issue with lighting on narrow Corridors.

If you look at the attached Image, you can see that at the first image (Flat normal) the ceiling edges but also other edges have strong contrasted edges, it looks unnatural and terrible.
At the second image you can see (green area) that the edges are barely visible, very smooth transition, lighting looks great - However! the right wall and ceiling shows really strong Artifacts.
(the Blue line marks a 90° angle on the geometry)

Lighting Issue.jpg

I have tried various solutions that came to my mind:

  • mixing flat and smooth geometry = Barely an Improvement, new transition issues between flat and smooth geometry
  • re positioning the lights = not practicable for smooth faces, on flat faces it can improve the hard edges quite a bit but then the lights will be at awkward positions causing new issues
  • AO and DFAO to cover the hard edges on flat smoothing = mediocre effect when shadows disabled on the light, 0 effect when shadows enabled (disabling shadows is not an option)
  • Using Spotlights or Lightprofiles = no improvement
  • Increasing the Lightsource radius/length = no effect on flat, turns black artifacts into white super glossy artifacts on smooth

Using more lights to cover the problematic off other lights is probably too expensive. Skylight is used and helps to decrease the hard edges for flat smoothing, but I require a Day cycle and during nights the skylight needs to be tuned down and on days the lights are not in effect so the influence of the skylight is negligible.