Please check for the following:
a. Check call forward latency in the indoor unit. It should be ON and to be set to a minimum 5 seconds.
b. Check if ring alert is ON in the app’s setting page and click on synchronise time option.
c. Check internet speed. Broadband upload speed to be at least 2 Mbps or above and Wi-Fi router to be of 2.4 GHz frequency.
d. Check for updated app software on Android play store or iOS.
e. Allow all permissions in Android and iOS while installing the app.
f. Battery saver and data saver mode should be disabled on the phone.