Make sure the speaker is connected to the AC adapter, and the adapter is plugged into a live outlet.
Make sure that you are connecting to a personal network (2.4Ghz, 802.11 b/g/n) and not an enterprise network such as in a business setting or college dorm.
Make sure your device is on the same network.
If the issue persists, restore the Alexa Speaker to the factory settings. Press and hold the “Alexa” button for about 15 seconds (a voice message will let you know when the unit is being reset) and try again.