According to DSM Update 3: I installed it manually on three different devices (each of them at different physical location and network). Installation was OK, everything seems to work correctly, BUT for me, the process of getting a new Lets Encrypt certificate DOES NOT WORK, not even on any of those three devices. Of course I deleted the certificate first to create it again from the scratch, but it just does not work.
Anyone lese has the same problem as me??? Port 80 and 443 opened, I even disabled firewall on my NAS for a while, but no success..