[libvirt-users] Shutdown problem from virsh

Hi everyone, On a server running Debian 9, I have multiple KVM guests automatically started at boot by libvirtd.service and running in the background. When I shutdown this server, libvirtd.service automatically and gracefully shut them all down first. So, every thing is fine so far. Recently, I've added an additional KVM guest and this one does not respond to a shutdown command from virsh and therefore messes up the shutdown of the whole Debian 9 server. The things is, this additional KVM guest is not a regular Linux guest. It is DiskStation Manager (DSM) 6.2 from Synology (with XPEnology as the boot loader). I know this setup isn't supported by libvirt nor Synology. Nonetheless, I wonder if anyone would have idea on that matter ? Even some suggestions might help me find what needs fixing. Thank you, Best regards, Thomas M.