Hi,
Thanks for your suggestion. I tried separate power supplies for all devices but unfortunately the issue still persisted.
Given that this is an as-yet unconnected system I've simply started from scratch and reinstalled the DuetPi img. The Duet3 mini board has successfully connected. I have since configured the HDMI touchscreen and Camera and the Duet3 is still connecting fine.
So, I'm not sure what I learned there!, Slightly concerning but hopefully it'll be fine if I don't meddle too much and I can go ahead and start wiring-up and configuring the CNC.
Many thanks for your replies.
Best wishes,
Jason