I really don’t know why it happens, what I can say is that using proxies (UK/Germany at night time in Spain, which is my country, and US/Canada in the morning) definitely helped. But what really solved the issue was NetLimiter, after researching for hours I found a user in this forum saying he got it fixed by limiting msfs.exe at 38 mbps and that’s they only thing that worked for me.
Before using NetLimiter the download would become stuck at some point in the process, same as for thousands of other users who complained here.