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I've just realised you mentioned that the cards do work with Druful, so the drivers must be fine.

The issue is possibly a more generic Mach3 issue, as Win11 may reject certain DLLs if it think...

Unfortunately, although I do have a Win11 laptop, I don't use it that much, and I've certainly not yet had any reason to look at how the device manager shows unrecognised devices.

If the driver...

My guess is that the driver (DLL) isn't security signed, so won't work with Windows 11.
If you look in Device Manager, does the card show when plugged in, and does it show as having any errors?