Troubleshooting an IR remote control

The other day, my Sonos Playbase speaker stopped responding to the volume control buttons on my Apple TV Siri Remote Control. Here’s how I eventually resolved the problem.

The source of the issue proved difficult to diagnose because infrared is (of course) invisible light. I couldn’t determine if the Sonos was no longer seeing infrared signals, or if the remote was no longer sending them.

If you have a remote control that suddenly and inexplicably stops working, I hope these steps will help you in solving the problem.