Hello

Did you tried the "default" post processor ?

I have had a look on Duet Gcodes and it looks like very standard.

If you board is a version older than RRF 1.18, the G2 and G3 (arcs) are not handled. If it is the case for you, you can change a setting in the post processor to force arcs to be written as multiple straight segments. For this, go to the system tab, select the post processor you're using and change Arc Output to Convert To Line and set a max deviation value for Arc To Line Tolerance.

Options - Arc To Lines Tolerance

If Arc Output=Convert To Lines is used, this value controls the maximum allowed error when converting arcs to lines. Smaller tolerances will result in smoother curves but larger files.
++
David