Your speaker might be out of range from your router. Try this:
– First, place the speaker as close as possible to your router.
– Then turn the speaker off, pull out the power cable and wait for 30 seconds.
– Reconnect the speaker to power, and wait until it connects to your network again. A sound is heard when the speakers have connected again to your network.
Go to the app and see if the speaker appears in My Speakers view. If not, close app and restart.