Tuning off all components with Apple TV, Dennon Receiver, and Sony TV
I can turn on all components via the Apple TV remote but when I turn off the Apple TV the receiver turns off but Sony TV stays on, then it turns the receiver back on.
The turning on and off of all HDMI components in the setup depends on CEC. How CEC is implemented relies on each device manufacturer. Most devices have an on/off setting for CEC as a whole, but rarely on individual CEC functions. Each possible CEC function is optional for manufacturers.
Please verify the CEC settings on your Sony TV. Sony may use the trade name ‘BRAVIA Link’ or ‘BRAVIA Sync’. With CEC off, it wouldn’t listen to CEC commands (suggestions) from other devices. Also verify with the manufacturer if CEC on this model supports turning it off (setting to standby) through CEC from another device. Some TV manufacturers presume that their device is the central hub that controls peripherals, thus not always listening to what other devices suggest to do. The Apple TV and Siri Remote can’t make TVs do things that they’re not programmed for.