In the last couple of Android updates I've found an issue when playing music via the Chromecast device on my TV. It seems once the screen sleeps the phone disconnects from the Chromecast and doesn't continue playing music. If the power button is pressed quickly it will usually start to play again.
The only way I've found to resolve this so far is to set my screen to never time out and turn the brightness down to minimum, but this not an ideal fix.
I'm using the built in music app on my Xperia Z5. I've tried other apps but they all do the same thing. There was an app called N7 that when used along with Toaster Cast, worked okay, but then Toaster, Cast stopped working.
Does anyone know how to fix this. I don't think that the phone is disconnecting from the router as I still get notifications when the screen is off.