We will look into this. Since firmware 1.8.3 is from a very long time ago, we haven’t been testing the new app with old firmwares. So in the meantime, if you can access the controller directly in a web browser, you should do that as the UI files associated with web access should work with that particular version of the firmware. The app is made to be compatible with most recent firmwares and as I said we don’t always do backward compatibility testing with older firmwares.