Problem with lightning/shadows

It is probably already solved this problem in another post, but I dont find the solution to these problems.
First a strange shadow appears here, i dont know how to remove it:

Secondly the shadow of this mesh has very poor quality, I would like to know how to increase the quality of this:

Third, part of this mesh is illuminated without having to do:


And finally, if increasing the number of indirect shadows (it was previously set in 0 indirect shadows) i get this problem:


Engine scalability settings are set in epic and i builded lightning at production quality, thanks for reading.


I think, strange artifacts is a wrong Lightmaps UVs. How to fix Lightmaps UVs you can read in this thread

Additiaonal info about tweaking lighting:

Thanks, i solved it with that info.