If the controller doesn’t behave as desired, you can set up your phone as a temporary mobile hotspot, reconfigure the controller to use that Wi-Fi, program a fixed schedule and test. The hotspot can then be taken down. When the fiber gets fixed, switch the controller back to your regular network.
If you don’t have big acreage, a neighbor’s Wi-Fi may be in range and you could ask nicely if they will let you connect your controller. This assumes that they are unaffected by your outage.