What were the lights doing when it was offline? If breathing red then the controller cannot connect to wifi. If breathing yellow or green for some it is no internet connection. The app will not work without a internet connection. If you have a phone you can turn off wifi and get the app up and select bluetooth and get the controller. It will let you turn output to either off, auto or on only in bluetooth mode.My Hydros Wave engine LE went offline 2 times in a month without any reason.