Hi Sergey,
we figured out an issue (kinda cosmetic) which prevents Royal Server V4 from running on a Windows Server Core installation.
Please find the details in our knowledgebase article:
Note though that Windows Server Core is still not in the list of supported operating systems and might not work in some scenarios.
Let me know if this helps and if you find any other issues with it (in that case open a ticket with us pls)
cheers,
Michael