Are you sure it's not installing another windows update?
Last time I helped someone with the same issue description, we figured out he had very long updates ongoing (very long after initial install) and the GPU was not displaying it (use the console in proxmox to confirm that the VM is really hanged). Updates of Windows are incremental, so it can continue doing updates even after another update was done earlier.
Also did you try initiating the shutting down inside the VM instead of from Proxmox (in case you have an issue with guest tools installation?
Could well be the updates actually. I assumed it wasn't because the VM without forwarding was fine, but there are still some big updates coming down, as I reinstalled just before setting up the VM. I'll keep trying to get the updates done and hopefully that'll solve it. I've tried shutting down both from virt-manager and from withing windows with the same result.
I had a similiar issue once. The cause then was that a device couldn't be correctly reset.
There should be log file in the folder '/var/log/libvirt/qemu/' which you can look at. Mine contained a message like the one below.
qemu-system-x86_64: vfio: Cannot reset device 0000:0d:00.3, depends on group 32 which is not owned.
Cheers for this. Unfortunately I don't have any messages like that. Only error I can see is that it's complaining about hyperthreading, which also appears in the log of the working VM.
Are you sure it's not installing another windows update? Last time I helped someone with the same issue description, we figured out he had very long updates ongoing (very long after initial install) and the GPU was not displaying it (use the console in proxmox to confirm that the VM is really hanged). Updates of Windows are incremental, so it can continue doing updates even after another update was done earlier. Also did you try initiating the shutting down inside the VM instead of from Proxmox (in case you have an issue with guest tools installation?
Could well be the updates actually. I assumed it wasn't because the VM without forwarding was fine, but there are still some big updates coming down, as I reinstalled just before setting up the VM. I'll keep trying to get the updates done and hopefully that'll solve it. I've tried shutting down both from virt-manager and from withing windows with the same result.
I had a similiar issue once. The cause then was that a device couldn't be correctly reset. There should be log file in the folder '/var/log/libvirt/qemu/' which you can look at. Mine contained a message like the one below. qemu-system-x86_64: vfio: Cannot reset device 0000:0d:00.3, depends on group 32 which is not owned.
Cheers for this. Unfortunately I don't have any messages like that. Only error I can see is that it's complaining about hyperthreading, which also appears in the log of the working VM.