If you have a big collection of smart home devices, you've probably renamed a few here, moved some to a different room there or otherwise changed your configuration (maybe even several times over). If you're like a lot of people (i.e., me), you probably forget to update Alexa after you make all those changes.
Unfortunately, you'll get a harsh reminder when you attempt to control these "ghost" devices with a voice command -- try telling Alexa to turn on a smart light using a device name it doesn't recognize and you'll see. "Sorry," Alexa will say, "I didn't find a device named [its new name]."
Do this often enough, and your smart home will become almost unusable. Worse: Detangling such a mess can be a tall order and, before long, you'll find yourself ignoring Alexa completely, controlling your smart home with myriad apps on your phone instead. How 2012.
You're in luck. There's a quick and dirty solution. It may sound risky at first, because, well, it is: You'll have to delete your entire smart home and start over, and you'll lose any rooms or routines you've set up. But otherwise the process is simple and should only take a couple of minutes. When it's finished (and you've rebuilt your rooms and routines in the app) you can go back to ordering Alexa around.
Here's how to do it.
You'll have to use Alexa's desktop site
First, put down your phone and pick up your laptop -- this has to be done on the desktop version of the Alexa website. Next, head over to Alexa's web interface (yes, that's a thing), then follow these steps:
1. On the menu on the left, click Smart Home.
2. In the primary pane, click Devices.
3. Scroll all the way to the bottom and click the box labeled Remove All.
4. In the popup window, click Remove to confirm.
5. On the next page, click the box labeled Discover.
Now, rejoice: Alexa has pinged all the various services you've linked (Philips Hue, Smart Life, etc.) and updated them all with the current names of all your devices.
There is, as mentioned, a downside. Doing this will obliterate any groups -- including rooms and speaker groups -- as well as routines you've created. That said, chances are, if you're having the kinds of problems that require a nuclear option such as this, they both needed to be revamped anyway.
You may need to do one more thing
I recently discovered a little quirk about Amazon Echos -- they remember. As in, if you unplug an Echo device and, only to retrieve it later and reconnect it to your smart home, it remembers the names of devices on your network when it was last connected. This can wreak its own kind of havoc on your smart home. The only way I've found to fix it is to nuke the device itself -- (follow the link for detailed instructions on older devices).
On third- and fourth-generation Echo and Echo Dot devices, press and hold the Action Button for 25 seconds (the light ring will pulse orange then turn off). The light will come on again, this time blue. Wait until it turns orange to indicate it has returned to setup mode.
To reset Echo Show devices to factory settings, press and hold the Mute and Volume Down buttons for 15 seconds or until an Amazon logo appears.