@MJAussie360:
…Instead, I got "Could not establish a connection to the Duet firmware! Please check your settings and try again"
I tried to go through Pronterface to check and it threw this error "WiFi module started Error: Failed to initialise WiFi module, code -10" Then it reverted to this error "Received opcode 0000013e length 0 data" constantly
For anyone else getting this error, it means that the version numbers of DuetWiFiFirmware and DuetWiFiServer are out of step. You can comment out the M552 S1 command in config.g to prevent the wifi module starting up. Then run M115 to check the version number of DuetWiFiFirmware. If that shows 1.19 then copy DuetWiFiServer-1.19.bin into /sys and rename it DuetWiFiServer.bin. Then you can run M997 S1 to install it.