Resolving Call Connection Failures in Air-Gapped Mattermost Deployments

Issue: Users may experience call connection failures, receiving the error:
"Call connection failed: We couldn't join the call because the connection timed out."
This occurs in air-gapped Mattermost deployments, particularly when behind a proxy like NGINX, and there are no specific errors in the server logs.

Cause: In air-gapped environments, the Mattermost server may default to using public STUN servers to establish connections. Since the environment is isolated from the internet, the server cannot retrieve a public IP address for the local interface, causing connection timeouts during calls.

Solution: To resolve the issue, configure the iceHostOverride Setting to use the internal IP address of the Mattermost server:

1. Update Configuration: Modify the Mattermost configuration to specify the internal IP address (the host IP) for the iceHostOverride setting to prevent relying on public STUN servers.

   Example configuration:
   
   ServiceSettings:
   IceHostOverride: "your.internal.ip.address"