Can we define the network settings to use dynamic IPs for both versions of the board (WiFi and Ethernet) within one config or would this cause issues? This was my idea:
M552 P0.0.0.0 S1
M552 S1 to enable networking with dhcp client. (for both ethernet and wifi)
as a one-off, and prior to to M552, you need to run M587 for the wifi board to tell it which network to connect to.
i believe newer firmwares can use run-once.g for this?
edit: duettest.local would imply you've used old config from factory, should be just duet.local and its set by M550
edit2: one option would be to use conditional gcode to run M589 to create an access point and allow user to connect to the duet to input wifi stuff wihtout using the serial console or removing sd card to edit files.