I use the soundbar with the TV and the UPC box. Everything (soundbar, TV, UPC box) can be controlled easily with the UPC remote control.
But I had to try something with the cabling at the beginning.
Now it works with the following cabling: ARC of the YAS207 to ARC of the TV and HDMI of the YAS207 to HDMI of the UPC box.
I can only switch it on directly on the soundbar or with the Yamaha remote control.
When switching off, it works with the TV or provider box remote control.
The volume can also be adjusted via the TV.
Maybe new TVs have a system setting that starts the soundbar.