@pendragon99 The last version of RepRapFirmware available for Duet 0.6 boards is v1.26.1; see https://github.com/Duet3D/RepRapFirmware/releases/tag/2.05.1
Duet3D does not support the Duet 0.6 or 0.85 boards any more, but you can always get help from the community on these forums.

For firmware update instructions, see https://docs.duet3d.com/User_manual/RepRapFirmware/Updating_firmware
You most likely need to update the board to the latest version using Bossa: https://docs.duet3d.com/User_manual/RepRapFirmware/Updating_firmware

Duet 2 and Duet 3 boards support RRF v3.

Ian