Thanks for input!
I just ran the win-acme client and certificate can be seen in EAC on new server. But I cannot add SMTP service to it (IIS service works without problem). When I tick SMTP and click ok nothing happens, no message, and SMTP remains unselected. Any idea why this is?
May be a clue: When I start MMC on the old server and try to export the letsencrypt certificate it says "Cannot export private key, it is not marked as exportable". When I do the same on the new server with freshly installed certificate it says "Cannot export private key - key not found". I'm stuck for now, any idea guys?
Thanks
Stefano