VirtualBox: Windows 10 pro (guest) doesn't update

My host system is Ubuntu 18.04 LTS with ORACLE VirtualBox 6.0. I installed Windows 10 Pro as a guest system, and this is a properly registered copy that is activated.

The issue I have now is that when I try to update Windows 10 it runs for a bit and then returns an error message saying code (0x80240fff).

The strange thing is that on the same desk I have my laptop running the same copy of Win 10 Pro, and connected to the same network it does the update.

Any clue about this? I wonder whether this may be due to some bad setting in VirtualBox.