Sonos User Manual page 39

SONOS USER GUIDE
Controls and lights
Connector panel
Volume up (+)
Volume down (-)
Play/Pause
Status light
IR sensor light
Press to adjust the volume.
Note: You can also use the app and remote control.
•
Press once to play or pause music.
•
Press twice to skip to the next song (if applicable to
the selected music source).
•
Press three times to go back to the previous song.
•
Press and hold to add the music playing in another
room.
Note: You can't skip forward or go back when
listening to a radio station.
Indicates the status. For more information, see 
https://faq.sonos.com/led.
The IR (InfraRed) sensor receives signals sent by a
remote control.
When the Playbar receives a volume or mute
command, the IR light displays momentarily. 
You can adjust this setting so the light never displays.
Tap > Settings > Room Settings and choose
the room the Playbar is in. Tap Remote > IR Signal
Light.
IR repeater
AC power (mains) input
Digital audio IN (optical)
Ethernet ports