Sebastian, Could you be dealing with a locked screen where the first reboot command is sending a "ctl-alt-del" that unlocks the screen and the second reboot command send a second "ctl-alt-del" that is actually telling Windows-10 to reboot?
One way that might be useful to see if that is the case is to connect to the Windows 10 console and then send the reboot commands. You could see if the reboot command is doing someone on the console screen. Don Sebastian Arcus wrote on 03/02/2018 03:22 PM: > All the 8 Windows 10 vm's I have will only reboot if I issue the reboot > command twice. They simply don't react on the first reboot command. I use > virsh to issue the command - but I am guessing it is nothing to do with virsh > itself (but I am ready to be corrected on this). Has anybody else seen this? > I am on qemu-2.10 > > Searching in Google doesn't seem to suggest anybody else is seeing this - > which seems strange. >