@dc42 I just upgraded from 3.4.0 to 3.4.4 on my Duet 2 Wifi with Duex5. I lost my ability to control my Duex5 fan speed control. It was:
M950 F5 C"duex.fan5" Q500
M106 P5 S0.7 H1 T10

It's always at 100% now. Any ideas? I can change the max speed X0.7 and that works but not the S0.7.