Below script is just a example of a lua running on a ADCH++ (rev 504 or above) that can act both as a nmdc to adc redirector only (then you only need this script running) or act as both real hub and redirector on the same or different port .
This can not be used on a hub running a secure server port.
It sends a nmdc redirect to any connecting user, and based on the fact that the ADC protocol should ignore “Unknown” commands a client connecting in ADC mode will just drop that command while a client in NMDC mode wil follow it (based on its settings)
So it is possible to have the real ADCH hub running on port 411 and at the same time redirecting nmdc mode clients to the same port but then in ADC mode (if they support ADC).
Maybe there are problems doing this but so far non seen and have no doubt that if there are …
This could be made more complex by adding a redirect based on received nmdc tag, a max number of redirects by ip, … etc.