Another entry that will help that one person on the Internet who's facing the same problem I have.

You have an Acer Travelmate B117-M, and wish to back it up over its wireless interface to a network drive; using Clonezilla booted from a USB stick, not a DVD.

What to do...

Firstly, boot the laptop, press F2 to take you into the BIOS.

Go to the "boot" option, and change the option of UEFI from Secure to... whatever the other option is, I'm backing up my own device as I type this.

Go to the Clonezilla website, and download the "bionic" version. The different downloads are listed here: https://clonezilla.org/downloads.php

Install it on a USB key by, very carefully, following the instructions on: https://clonezilla.org/liveusb.php

Note - the stable version of Clonezilla loads the right iwlwifi driver for the Intel Wireless 7265 network card, but it doesn't work. Check the output of "dmesg" for further information, but I couldn't see any way of fixing tha easily.

Note - the size of USB stick needed is slightly larger than those old 256MB USB sticks you've got lying around... so don't bother.

Boot the laptop, press F12 to take you to the boot options.

Choose your USB key.

Boot into Clonezilla.

Use the alt key, and either F2 or the right arrow, to move to a terminal window. Type "sudo bash" to become the root user.

The instructions for setting up wireless networking are here: https://www.linuxbabe.com/command-line/ubuntu-server-16-04-wifi-wpa-supplicant, but the important lines are:

wpa_passphrase your-ESSID your-passphrase > /etc/wpa_supplicant.conf
wpa_supplicant -c /etc/wpa_supplicant.conf -i wlan0

That will associate you with your local wireless access point.

From there just run clonezilla as normal.

( a couple of extra notes: while trying to solve this I upgraded the laptop's BIOS to version 1.25, which I downloaded and ran from here: https://www.acer.com/ac/en/GB/content/support-product/6660?b=1 ; the Clonezilla USB key only booted when I set it up with an MBR partition using the "o" option in fdisk... or that might have been me forgetting to run "makeboot.sh" )