@Thitsa 

Unfortunately, there is no magic button in the app that can reboot the devices in bulk, especially if they are disconnected from the network. Devices are supposed to restore to the last state when a power outage occurs.  If that is not happening then we would want to look into that.  Due to the number of devices I would suggest reaching out to support through email support.usa@tp-link.com.  Let them know what is happening.  They will want to know the models, hardware versions.of each device.  They will also need to know the firmware installed on each device.  It would also be helpful for them to get device MAC ID and your TP-Link ID email so they can look on the backend and see if anything is causing this error.