Building lighting resulted into quite ugly shadow calculations

Hello there,

I am kinda giving up on this.
Had issues with importing my stuff from unity over UE and now struggling with pretty ugly shadow rendering.
Lemme say before someone points this: compressed shadows are disabled. Nothing else have been adjusted in the shadow settings (and even adjusting them afterwards makes no difference).
The models are plain simple meshes created in blender, they are single pieces put together (except the log at the very right in a pentagon-cut shape), they are not manually connected faces, vertices or borders.
The fireplace is one whole set, the log on the right is a standalone.

Mushy shadows on the log, some weird barcode-ish shadows on the stone, cut apart shadows on the sticks, and so on …

Might someone help me with this? I don’t want to go back to Unity.

Edit: Exported my files with the market #1 tool for FBX format: Maya. Guess what … no differences. The whole body looks just ugly. Even a simple cube looks as ugly as my lowpoly meshes. Can someone tell me whats going on with UE4?