This Clevo laptop is a new machine and like a lot of new machines, not all of its hardware has drivers in the current stable release of debian.
Happily, there is a driver for its rtl8723ae wireless networking device in the later 3.8 Linux kernel versions. So it’s just a case of installing the package called “kernel-package” and following the instructions in it, to make a new linux-image package with the latest drivers in it.
One small thing which tripped me up is that you usually need to write “make-kpkg –rootcmd fakeroot –initrd kernel-image” now. I forgot the “–initrd” option at first.