Thanks for your reply.
My chromecast is connected with an ethernet cable through an USB hub plug into a wall outlet. It works great. But Homey only find it when it is connected wirelessly.
I just want to turn on/off the TV. With google assistant there is no problem. I can create a routine where I write “Turn on the tv” and it works well.
Everything is up to date, I tested lot of apps but none can do what I want : “when I press a button then turn on the TV, speakers…” Google Assistant can turn the TV ON but can not be trigered with a button. Homey is the opposite haha ^^ I wish Homey could start a GA routine, it would be perfect.