Can't establish a connection to the domain due to an invalid certificate. Please contact your system administrator for additional assistance.

Issue Explanation

This message indicates that the app couldn't connect to the Ringotel server due to potential interception of SSL traffic in the user's network, where an unauthorized SSL certificate is being used. The Ringotel server exclusively accepts the Ringotel certificate, resulting in connection failure. This issue may arise from network filters intercepting HTTP traffic within the connected network. As communication between a Ringotel app and a Ringotel server occurs over standard HTTPS port 443, interference from network filter solutions can lead to this problem.

Possible Solution

To address this issue, please attempt connecting from an alternative network (Wi-Fi or cellular data).