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.
- I quickly determined that I hadn’t added any new nearby electronics or LED light bulbs that might be interfering with IR signals. A lesson I learned from a confounding situation several years ago.
- Using the Sonos app, I temporarily re-programmed the Playbase to respond to a TV remote it had not been previously trained on. When I was able to successfully do so, this established that the Playbase’s IR receiver was working.
- The Apple TV remote was still able to control the Apple TV, but that uses an RF connection, not IR. (Sadly, the Playbase is IR-only.) But this confirmed that the remote’s battery wasn’t dead. I recharged it anyway, under the theory that perhaps the light emitter had grown too dim. This didn’t resolve the problem.
- The next step was to reboot the remote. Yes, that’s a thing. After doing so, the problem was resolved. Yay!
If you have a remote control that suddenly and inexplicably stops working, I hope these steps will help you in solving the problem.