@drummmerboy 

Smart plug's schedule continues to function when the internet is down. However, if the smart plug experiences a power cut, the schedule will not continue until the smart plug reconnects to the internet to synchronize device time. 

You can try to enable a hotspot wifi in the garage and set up the smart plug with this wifi on another phone. The schedules should still work when the hotspot wifi is gone. 

It should be noted that since the smart plug cannot connect to the Internet to calibrate the time, the device time may become inaccurate over time. When something like that happens, just reconnect the smart plug to the internet.