Jitsi OK from external - no video conference from inside with more than 2 clients

Hello everbody,
due to the corona pandemic, I should set up a video conference server. I installed Jitsi on an Ubuntu 18.04. LTS with Docker.

Our Config: Firewall: Sonicwall with NAT settings on external Port 8443 to Port 443 to Jitsi
Port 10k UDP NAT to UDP Port 10k Jitsi Server
Port 4443 TCP NAT to TCP Port 4443 Jitsi Server

From external (WAN), you can access the videoconference with more than 2 clients - it works great.

Access from the internal network is not working. (more than 2 clients)

I logged the connection establishment with Wireshark. There you could see that the internal client contacts the STUN server, which returns the public IP address and the then client tries to establish the connection via the public IP.

This works externally(WAN), but not from internally network.

Here are a few settings that I have set.

Maybe you can help me.

Settings i have set in the Docker .env file:

Enable Lets Encrypt=1
https certificate was successfully added

Exposed HTTP port.


Exposed HTTPS port.


Media port for the Jitsi Videobridge


TCP Fallback for Jitsi Videobridge for when UDP isn’t available


STUN servers used to discover the server’s public IP.


Would U turn NAT be a possibility with your firewall?