I have a Philips android TV - an earlier model than yours.

I have it turning on and off, but I bought a Logitech Harmony Hub for the purpose.

Have you tried it after the Oreo update?

Normally, you'll never will be able to do it because when the TV is off, it just doesn't respond to anything, most of the people that can do it is because they have an outside hardware, like an nvidia shield or a Chromecast ultra or anything else that have HDMI CEC. At least that's what a technician from Google told me.

But it seems that it works for some people regarding this post on XDA (it has been discussed in the last two pages):

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https://forum.xda-developers.com/android/help/philips-android-tv-t2935545/page196

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