NextCloud10 + + Spreed Webrtc Server - No audio


I have successfully installed Nextcloud using VM from site & Spreedme Server in the same VM.

Spreedme app is installed in Nextcloud.

People can join in the room and all are working fine including the video call.

Video call - Audio and Video are fine.

Primarily we are planning to use this setup for training purpose, where we will share the desktop/screen and all participants will be only participating with their audio.

However, when people join the room, we can see list of participants in the right panel but audio is not there.

Also, we could not do video conferencing for more than 2. We are unable to call other participants when we are in a call. Nor they can call us when we are on a call.

Can someone please suggest what is missing?