A number of people of have tried to install Windows on Cockpit on OMV 5 and failed. Many seems to be going back to OMV 4 and Virtualbox. Here is what I did to install Windows on Cockpit:

1. Install OMV 5. Had to use ipv6.disable=1 in the grub argument because it hung on getting an ipv6 address.
2. apt-get update
3. apt-get dist-upgrade
4. apt-get clean
5. reboot
6. Login to web interface and apply changes (caused by openmediavault package upgrade).
7. reboot (probably not necessary but doesn't hurt)
8. Login to web interface
9. From System -> Network -> Interfaces, Delete the ethernet device but DO NOT apply changes.
10. Add a Bridge using your same network settings as the ethernet device. I used DHCP.
11. Apply changes. The IP address will probably change if you are using DHCP.
12. Install omv-extras. I used the script from the command line
13. Install Cockpit from omv-extras Cockpit tab.
14. Open Cockpit web interface with Open Web button on Cockpit tab.
15. Go to Virtual Machines tab. It should recognize one network.
16. Create a VM
    1. Enter name
    2. Pick ISO
    3. Pick any OS since Windows is not in the list - I used Haiku. You can edit with virsh edit [VM-NAME] if it causes problems -https://wiki.libvirt.org/page/…nd_and_how_do_I_use_it.3F.
    4. Set disk size. I used 40 GB
    5. Set Memory. I used 4 GB
    6. Uncheck Immediately Start VM
    7. Update vCPUs from 1 to 2
    8. Click Install

Quote from crashtest

You might consider putting this in the Guides section, to keep it from getting buried. It's a useful How-To.

Moved. I was hoping to get a little feedback on it whether it was working for people but I can get that in the Guides forum too.