I have seen a lot of posts about problems getting the duet to talk to laptops and thought I would share something I found that solved the problem for me. Although the laptop could see the duet, It couldn't read the SD card and the USB connection was very hit and miss. I assumed I had dodgy board. However I managed to source through a colleague a second duet board (a much older one that came with one of the first RS printers) - it worked fine, so I triumphantly updated the firmware to the latest version as per commissioning instructions, only to find that it promptly now did exactly the same thing as my original board

The only thing they had in common was the SD card, which was working fine before I updated the firmware. I dug out another, better SD card that I had laying around, formatted it, added the relevant files and voila - all sprang to life on both boards! My conclusion...that the supplied SD card worked on the very original firmware, but failed to be good enough for the later version I installed, so maybe worth a try if you are experiencing something similar