The most common issue: the device hears you but doesn't react, or the wake word stops working. First, check that the microphone isn't muted — there's a physical button on top of the Echo device. Then open the Alexa app and go to Settings > Device Settings to confirm the wake word matches what you're saying. If the light ring spins orange, the device has lost its Wi-Fi connection and can't reach Amazon's servers.
Echo devices are sensitive to 5 GHz band instability. If your router broadcasts both 2.4 GHz and 5 GHz under the same name, the speaker may switch between them and lose connection. Try setting a separate SSID for 2.4 GHz and connect Alexa to that one. Also keep the device at least a meter away from microwaves and cordless phones.
If a third-party skill opens and immediately closes, the issue is usually a broken link between the skill and your Amazon account. Disable the skill in the app, wait 30 seconds, re-enable it, and re-link your account. If the skill requires a separate login (like a smart home service), make sure those credentials are still valid.
When playback fails or buffers constantly:
If the mobile app hangs on the home screen or devices don't appear, clear the app cache (Android: Settings > Apps > Alexa > Clear Cache). On iOS, delete and reinstall the app. Make sure you're signed into the correct Amazon account region — accounts registered in the US won't sync properly if the app region is set to EU.
Alexa can't control your lights or thermostat? The device may have lost its cloud connection. Open the app, go to Devices, and check the status. Run Discover Devices again. If the issue persists, disable and re-enable the relevant skill — most smart home integrations rely on OAuth tokens that expire without warning.