Two-Way intercom from Battery Doorbell not working after ringing

Following Usecase happend now a lot of times and is very disappointing:

If someone is ringing our Battery Doorbell (connected to Wifi within 3m, best connection) I am notified by my Eufy iOS App (latest version of iOS and Eufy app) via Push Notification.

If I click on the notification the video stream is loading (all good), but when I push the phone button to open the voice connection that doesn´t work most time directly. I had a lot of times the situation that the ostman is going away while talking to them. Asking them next time they told me that they could not hear anything.

So for me there needs to be improvement on the intercom functionlity.

Anyone elese with the same intercom issues?