Whenever a piece is hardware is not supported (or badly supported), you can
hope that a more recent kernel will solve the problem. It takes a few
minutes to try, following the instructions on https://jxself.org/linux-libre/
But, again, I doubt a more recent kernel will support your Wifi chip
Well you can try the latest Linux-libre kernel (version 4.19):
https://jxself.org/linux-libre/
But don't hold your breath. You will certainly need a USB adapter such as
those http://libre.thinkpenguin.com and http://tehnoetic.com sell (both ship
worldwide).
They are non-free:
http://changelogs.ubuntu.com/changelogs/pool/multiverse/v/virtualbox-guest-additions-iso/virtualbox-guest-additions-iso_5.1.38-0ubuntu1.16.04.1/copyright
