@BartW22 if your resonances are at low frequencies then you should reduce the sampling rate (M955 S parameter) to between 200Hz and 800Hz and increase the sample time e.g. to 4 seconds. Also un-check the box that causes samples to be taken throughout the move, because you will get more accurate low-frequency results if you sample only when the move has finished.
The minimum input shaping frequency currently supported is around 5.8Hz on Duet 3 boards and 6.2Hz on Duet 3. I can reduce it in 3.6 firmware, however a low input shaping frequency will lead to larger artefacts unless the print speed is also reduced.