So let me get this straight, the only “PXE Reboots after…” is happening on the VirtualBox VM?

I am aware of issues with Virtual Box, specifically, and the only fix that I found (if you’re using undionly) is to do a power off, then power on. The other, more appropriate, fix is to use ipxe.pxe file rather than the undionly, but i also know that not all Physical systems will work with the ipxe.pxe.

When these boot into Windows or other operating system, like the LiveCD of Ubuntu, are they able to get an IP address from DHCP? Can you release/renew without issue?