@sc2024,

Unfortunately, this is the nature of Wi-Fi devices, as your phone needs to communicate with the device during the network change via its inbuilt setup network, not just to send the new credentials through its typical data connection.

Saying that, our teams are aware of the pains that this can cause, as I am sure we have all fallen victim, and have been working on a solution. The first step in this was adding BT connectivity to our devices for setup, allowing a secondary connection to the plug while the Wi-Fi is being configured and there is more to come. As for changing networks, we will begin to learn more about what was developed as a solution as it is a part of a whole-ecosystem feature allowing the quick configuration of Wi-Fis across devices and even routers; however information about TP-Link Simple Setup (TSS) is still difficult to come by. 

For now, if your new router supports an IoT network, consider enabling the network and using the settings from your old network - oftentimes this will alllow your devices to at least regain their connection using your new network. Otherwise, you have to perform a soft reset (5sec compared to 10sec) on each device. This soft reset will remove the old network settings and allow you to connect the device to your new network, but will keep all of the previous settings such as the schedules, device name, automations, and room.