The Sonoff Device IP Finder as the name suggests assists users and specialist to find the current IP address for any Sonoff Smart Switch with the stock firmware without having to upload new firmware. This issue arises when you change routers or the IP address changes as all Sonoff switches only support DHCP. This makes the issue go away.
This tool uses the stock firmware from Sonoff, there is no need to change the firmware to manage Device ID to IP, there is no need to send complex REST API calls to find the device IP. Most applications if not all use different firmware from other other companies which can now be easily achieved right out of the box.
How to Video at https://youtu.be/lhZ1zeOb3dU