Why is my ICE Gathering Status 'Host Only'? Troubleshooting WebRTC Failures

Common firewall issues and configuration errors that lead to failed ICE candidate collection

When using an ICE Server Tester, you might sometimes see that only "Host" candidates are gathered, but no "Srflx" (STUN) or "Relay" (TURN) candidates appear. This is a clear sign of a connectivity bottleneck.

Common Culprits:

• UDP Blocking: Many corporate firewalls block all UDP traffic by default. Since STUN/TURN primarily use UDP, the discovery process will fail.
• Incorrect Credentials: URN servers require a username and password. A single typo in your iceServers configuration will result in an "Unauthorized" error, preventing relay candidates from showing up.
• NAT Hairpinning: Some routers do not allow a device to connect to its own public IP address. This can make local testing difficult.

How to Fix it: Always start by testing with a known public STUN server (like Google's). If that works but your custom TURN server doesn't, the issue is likely in your server configuration or your firewall's port 3478.

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