So strange conflict between max DAC and RP2040 arduino card controling motors!

Good morning,
I have a very strange problem:
I control an installation with robotics from max/msp, to control pendulum robots.
Max uses OSC via a router to an RP2040 Arduino Card inside the pendulum, to control the motors.
Another rp2040 card in the same pendulum sends gyroscopic data back to Max. This data is smoothed by a piece of patch using the rampsmooth~ object, requiring the opening of the DAC. I use this smoothed data to control movement in real time, and also to interact with sound, requiring in any case that max's DAC is activated. 

So far everything was working pretty well. But today the motors started to work abnormally. When I turn off the MAX DAC, everything works normally!

I therefore conclude that the problem comes from there, but I cannot explain it, especially since it has been working without problem for several weeks.

>>>>> Would anyone please have an idea why the DAC interferes with the operation of the motors when there is only a very indirect link between them?

My configuration:
MacBook Pro M1, OS 14.6.1, 16 gigabytes of RAM
Router TP-link Archer AX10
Mornsun 48v power supply
Arduino RP2040 board with 48v > 3.3v converter
3.3v > 5v conversion card for sending Dir and Pulse commands
Driver Stepperonline (DM542T)
NEMA 23 Motor (23HS30-2804S-RV30-G30)

I thank you in advance
Virgile