Control serial only or telnet Denon AVR devices like the Denon AVR3806 over IP with a serial to IP gateway.
The three zones of the AVR will appear as seperate media devices to control.
If this helps you, or you are just generous. I do love coffee.
Add the integration.
Supply a name for the integration - or stick with the default if you are only going to add one. Supply the hostname (or IP address) and port of your IP to serial gateway.
Once connected, the three zones will appear with relevant controls.
PR's are more than welcome either to the HACS component or the Denon AVR Serial Library.