I have been doing some research on why wifi failed in my latest attempt to install MX18 on this Acer Aspire 3. I searched "no wifi post-install" on google which first took me to a Win 10 forum and that led me to an Acer and then Lenovo forum. Apparently, on newer Acers and Lenovos that use the InsydeH20 Set-up Utility, there is a glitch that causes Gnome to activate Airplane Mode during the install. I then searched for 'Airplane Mode Debian Stretch' which led me to this page from the Debian forums :
http://forums.debian.net/viewtopic.php?f=5&t=134115
The gist of which is:
First, as root, run:
then, if it shows that wireless is software blocked, as root run:
followed by:
Note that it appears that setup utilities other than InsydeH2O provide the utility to disable Air Plane mode. There was talk in the lenovo forums on how to disable Air Plane mode by disabling a module in the bios.
I haven't tried this yet, but will tonight or tomorrow morning.