DIAGNOSIS The Wi-Fi module in the grill has lost its configuration or is stuck. A weak signal during setup is the usual culprit.
FIX Perform a hard reset on the grill's Wi-Fi. On the controller, press and hold the 'Wi-Fi' button for 5-7 seconds until the icon blinks rapidly. This clears the old network info. On your phone, forget the 'Z Grills_XXXX' network. Close the app completely. Re-open the app and follow the setup steps again, with your phone very close to the grill.
IF THAT DIDN'T WORK Ensure your phone is connecting to your 2.4GHz home network, not 5GHz. The grill module does not support 5GHz. Check your router settings.
HEADS UP The grill's Wi-Fi range is very short—about 30 feet with a clear line of sight. Walls and interference will break the connection.