@flopo76 one for @chrishamm to fix with the config tool

Unfortunately that doesn't tell me much.

Can you try setting a range for T in your commands? T25:50 for instance.

Can you send M98 P"config.g" and M122 in the gcode console and share the results?

@maximyz3d DWC is programmed in VUE.
There are some guides on creating plugins. Never tried it myself though

@maximyz3d RS485 support has been added in 3.6 (still in beta) so you can use that to read/write registers.
Otherwise you've got UART, MQTT or HTTP

@maximyz3d you won't be able to sync them and use them all together.
your only choice is CAN-FD.
What is the maximum cable run length you would be looking at?

@SpeedyDad sounds like a config error.
the "Tool Fan" in DWC is the part cooling fan of the currently active tool and not the hotend cooling fan

No problem at all.

@awitc ok. Just wanted to mention that theres a fork of the duet firmware which runs on an STM32F4 (only the STM32F407 and STM32F429) which can have an spi2can module added so it can talk directly over CAN-FD to the duet 3.
Although that probably won't help you with the control of the extruder.

Have you added M575 in your config to enable the UART connector?

@awitc what are you ultimately going to use the STM32F4 based board for? Which specific STM32F4 processor does it run?