Older Denon AVR with RS232

Does anyone have this working over a serial to LAN adapter?

I donā€™t have any personal experience to offer, but I can point you in a good direction. Bajansenā€™s library on github uses pyserial to establish serial connections, which allows you to supply a URL as the serial port. The formats supported are documented here:

https://pyserial.readthedocs.io/en/latest/url_handlers.html#urls

If you want to guess whether a particular adapter works, look for peopleā€™s experiences with it and pyserial.