You better use this other app and DTH. It works better and has more functions, mute, power save screen off and refresh the status every 5 minutes.
Important, these LG TVs if you turn them off with the remote control or from the app, you can only turn them on again with the remote control.
If you just want to turn the TV on and off, you can put a smart plug, zigbee or zwave for the TV. As the TV remembers the last state, you can always turn it off and on with the smart plug, which is almost the same as the app does.