Any USB/Ethernet controller suggestions?

[A_Camera]

That just shows how little you actually understand about the drives and the technology in them.
The DM542 is using technology that must now be well over 20 year old now, just like Gecko are still using in most of their stepper drives. The only real change to the designs has been to use modern components, but the basics of operation are still the same as 20 years ago. It's just smaller components are used.

AM drives, although officially obsolete within Europe (they were superseded by the EM series), are still an active product produced by Leadshine. They use far newer technology, and monitor how the motor is reacting to the voltage/current applied to it, which is how they implement anti-resonance, auto-tuning, and stall detection. DM/DQ drives do not have that technology in them, regardless of when they were made.

Please, don't use "DM/DQ" as if they were equal, they are not. The DQ are Leadshine copy products, the DM are original Leadshine products. There are also many DM models, some outdated, some not, some digital, some analogue. And not all DM products use 20 years old technology, and even the AM882 is about 10 years old... so it is pretty far from the latest and most modern.

Apparently you didn't read what was stated by Leadshine on their own web page, which I linked to.

Legacy leadshine stepper drives which may have been discontinued or will be discontinued. Those stepper drives are not suggested for new applications anymore. You can contact us if you still have the needs to use any of them.

AM882 is one on that list, the DM542 is NOT on that list.

Leadshine's DM series digital stepper drives are DSP-based innovative products adopting the latest stepper control technology. Those stepper motor drives feature anti-resonance, low-speed ripple smoothing, extra-low noise, and low motor heating, therefore they can offer excellent performance for stepper motor controls.

The DM542 is on that list.

DM in itself is not equal to obsolete technology and not all DM are outdated products. The DM542 is, at least according to Leadshine, not an outdated model yet. Yes, it will probably be replaced by the EM542S and will be obsolete. The EM-S series seems to be a match of the DM series, while the EM series replaced the AM series, higher current and voltage drivers.

BTW, what is "officially obsolete" is obsolete. At least according to me. I am not saying that the AM882 is not better than my DQ542MA, of course I'd expect it to be better for that price, but it is a huge overkill for 3A motors.