It's network related..
I come to idea to chec network after trying to run Xbox app from other pc in the same network witch behaved same as on my gaming pc.
And after one night of leaving my msfs2020 to try to download I noticed that there were download of about 2gb during the night. I analyzed traffic on mikrotik and coculluded that there where network error on our primary ISP connection, and during redundant connection to other ISP download begon, until primary ISP comes back then download stops again...
I isolated given IP... So anybody with problems should ckeck firewall rules and connectivity to ms servers.
I am glad that I helped
Cheers from Montenegro
DANILO