Now that you're at 3.0 you should probably update to 3.4.1
3.0 was a very early release, much has changed.
Updating now is as simple as uploading a single zip file to the system tab in DWC. Do not decompress it first.
https://github.com/Duet3D/RepRapFirmware/releases/download/3.4.1/Duet2and3Firmware-3.4.1.zip
And if you're coming from 2.03 you should probably generate a new config file set.