It seems when my TV turns to the HDMI3 source (that is connected to Vero), it wakes the Vero 4K+ from standby mode. This doesn’t play nicely with my home automations. Is it possible to change this behaviour?
I tried the setting for Peripherals > CEC adapter > Send ‘inactive source’ command at shutdown. But this did not have any effect. I don’t know where else to check?
Are you using CEC?
The relevant setting your looking for is to disable “switch source to this device on startup”.
The “send inactive source” command is just sending that message to other devices on the CEC bus. What the other CEC enabled devices do with that information is up to them (which is to say they will probably do nothing obvious).
Thanks. Funny how that setting description lead me to a very different interpretation. Might be a translation issue. Or my ignorance 
There is a bit of black magic when it comes to CEC. As long as you have “enabled” turned on and your devices to power on/off on startup/shutdown is set to TV (including the AVR is normally the wrong choice) then the power and source commands previously discussed should work. I personally keep everything else off/ignore with the exception of action when switching source which is set to pause playback (personal preference obviously).