For me it’s working.
The update is done via UDP from Yamaha to Homey. It could depend on your network configuration.
As first try restart the app. Perhaps the connection is possible then. If not, please send me a diagnostics report after app restart. Perhaps I can see a reason why update registration does not work.
Hi!
Through googling I got this information from Gemini as a google result:
“API Command: Use the MusicCast HTTP API to play the URL.
http://<MUSICCAST_IP>/YamahaRemoteControl/app?YYYYY/netusb/playUrl?url=http://<YOUR_SERVER_IP>/tts.mp3“
is this true/correct ?
And what are/is this “YYYYY” ?
Could you probably advise or even add the function to your app to play an(y) url ?? I’m trying to connect googke tts (url) to my Yamaha musiccast speakers so I can play any message through them like in Home assistant (it’s working there already for years but still not here with Homey pro. )
Maybe you could even take a look at the HA yamaha GitHub for some hints/help .
So basically trying to combine your app with the google services app for homey using google translate url for tts :
KI is fascinating 
/YamahaRemoteControl is an URL used by the “old” XML API used for AV Receiver.
But there is only one (1) URL: http://<IP>/YamahaRemoteControl/ctrl and the commands are sent as XML body like:
<YAMAHA_AV cmd=“PUT”><Main_Zone><Input_Sel>NET RADIO</Input_Sel></Main_Zone></YAMAHA_AV>
There is no documentation about all functions. But I only know basic functions used in the AV Receiver device.
The other used API is the REST API (JSON based). The base URL is http://<IP>/YamahaExtendedControl/v1.
But NetUsb is only used for playback controls like play/pause/forward etc. like:
http://<IP>/YamahaExtendedControl/v1/netusb/setPlayback?playback=stop
And for this API, only USB list options are documented. But that’s only navigating through a list as if you were in the menu displayed via HDMI. I think a kind of DLNA is also possible via list navigation.
But there is no real network control.
