I don't think Virtualbox has a UEFI option, so I think virtualbox is (rightly) booting legacy. But still it can't boot from that ISO I just tried VMWare Player I notice that one can choose UEFI or not ...

PXE stands for Preboot Execution Environment and is a client-server interface that makes it possible for computers to be booted from a remote server on a network. This makes it possible for you to ...

If you find yourself with a mismatched VirtualBox and VirtualBox Extension Pack release, such that VirtualBox itself cannot resolve, Jack Wallen shows you how to fix this from the command line.