@Sytek Edit - The Duet freezes without the thermal warnings and the stack underflow command. The commands I'm sending to the Duet from the PanelDue are just Move and M408: Report JSON. The config file was made quite along time ago and the firmware was recently updated.

config.g

The part number for the Micro SD card socket on the Duet WiFi/Ethernet is DM3AT-SF-PEJM5(40). I think the Maestro uses the same one, but I am not certain.