The "Could not establish connection; please try again or contact support." message is displayed when our system failed to retrieve the contact’s data.
Please confirm that all systems are operational on our side by visiting Talkdesk status page.
Also, make sure that you are using an Ethernet connection and not WiFi. WiFi lacks reliability for voice communications as it is prone to increased latency and interference from other devices.
Please check this article for more information on why we strongly recommend using an Ethernet connection.