Thin walls changing thickness on layers with windows/ceiling (Architecture).  

Thin walls changing thickness on layers with windows/ceiling (Architecture).

Hey all and thanks for reading my topic.

I received my first 3D printer ever, the prusa mini a week ago and so far I´m really happy with the printing result.
All models from prusa and other sites are printing perfect without any issues. 
Even a self modelled part printed fine and without any problems.

But currently I am very frustrated because I don´t know whats wrong and what I can do to fix it.
This is a 1:250 house modelled in 3Ds Max which I want to print, but I always get these strange changes 
in wall thickness... If there is a better wording for the issue, let me know :)



Print: Prusa Mini - Prusament PLA - 215/60 Temp - 0.15mm Quality Mini Profil

You can clearly see how the base is super smooth and then, when the first window holes appear it suddenly makes
the wall thinner. Then the ceiling makes the wall thicker and so on and on. The issue isn´t just on one wall, 
it continues along all sides. I tried it with "detect thin walls" on and off: No difference. 

Also I remodelled it with different wall thickness like (0.87/0.9/1.29/1.3) but it didn´t changed anything. 
If I only print one wall with holes there won´t be any issue, it prints just fine.
Here is a screenshot from the slicer:



Does anyone have an solution on how to get this printed with enterly smooth walls?

I uploaded the 3mf, stl and a 2016 3Ds Max file I used, maybe you will find the problem I couldn´t find.
Download/View the files on OneDrive

If you need anything else to isolate the problem, just let me know.
Thanks for reading and thanks in advance for every helpful advice.

Best wishes,
Sven