You can turn on the TV using only this library

[mirekpe]

Every (I think) TV turns on when you press the channel select key on the remote. I think it works with this library too, as long as the fast start option is enabled on the TV. E.g.:

Turn on

tv_control = TvControl(client)
tv_control.channel_down()
tv_control.channel_up()

and then select the source (HDMI1)

source_control = SourceControl(client)
source_control.set_source(sources[0])

[supersaiyanmode]

I didn't know this at all -- thanks so much! I thought fast-start option makes the TV listen for wakeonlan packets and nothing more.

Did you establish a connection and then turn the TV off? In other words, can you confirm if you're able to establish a new WS connection to the TV that has the display turned off?

[mirekpe]

Yes, I have this Python script in Windows StartUp and it seems to work. Without WOL. Of course, after logging in on the laptop screen (the picture on the TV is not displayed). After a few seconds or so, the TV turns on. This library is really great! I've been looking for something like this. :) Now, when a business or private laptop starts up, the TV changes the input by itself. This bypasses the lack of HDMI CEC in Windows.
I will test it for a few more days. I came across this library only today. I'll write in a few days whether it works without problems.
If it continues to work, I'll be glad to see someone else use it.
THANKS!

(My TV: OLED55CX9LA)

[mirekpe]

This trick unfortunately does not work. @supersaiyanmode is right. The TV turns off the network interface and listens only for magic WOL packets. I probably hit a time when some WebOS application was keeping the network connection even after the TV was turned off (maybe downloading updates).

As a consolation, I wrote very simple code to wake up the TV, using the built-in modules and ping to check if the TV is already responding.
I've rewritten the IP and MAC addresses from the TV settings. Unchangeable IP, I ensured by reserving the address on the router. I know it's all a bit primitive, but it works now.

from pywebostv.discovery import *
from pywebostv.connection import *
from pywebostv.controls import *

import socket, os, time

broadcast_adr = '192.168.1.255' #your broacast address
tv_adr = [
....{'ip': '192.168.1.65', 'mac': 'BBBBBBBBBBBB'}, #your lan
....{'ip': '192.168.1.64', 'mac': 'AAAAAAAAAAAA'}] #your wifi
....# 1. For the first run, pass in an empty dictionary object. Empty store leads to an Authentication prompt on TV.  store = {}, note key
store = {'client_key': 'a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1'} #your key

soc = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
for _ in range(20):
....for adr in tv_adr:
........if os.system(f"ping -n 1 -w 300 {adr['ip']}")==0: #linux: ping -c 1 -w 1 #mac: ping -c 1 -t 1
............client = WebOSClient(adr['ip']) 
............break
........# Wake On LAN
........soc.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST,1)
........soc.sendto(bytes.fromhex("F" * 12 + adr['mac'].upper() * 16), (broadcast_adr, 9))
....else:
........time.sleep(0.75)
........continue
....break

client.connect()

for status in client.register(store):
....if status == WebOSClient.PROMPTED:
........print("Please accept the connect on the TV!")
........print(store)   # {'client_key': 'ACCESS_TOKEN_FROM_TV'}
....elif status == WebOSClient.REGISTERED:
........print("Registration successful!")

source_control = SourceControl(client)
sources = source_control.list_sources()
source_control.set_source(sources[0])