Here’s a very handly link to test what resolutions your webcam supports: webrtchacks.github.io/WebRTC-Camera-Resolution/

• Chrome, go to chrome://webrtc-internals/
• Firefox, go to about:webrtc
• Edge, go to edge://webrtc-internals/
• Safari, if available in menu bar, go to Develop -> Show Javascript Console

This will show you more details on your WebRTC connection and can help to troubleshoot any issues.

Here’s a pretty good explanation of STUN, TURN and ICE.

Some hosting facilities’ virtual servers may not be able to transmit their public/private IP addresses to Red5 Pro server. This information is necessary for the ICE negotiation in WebRTC. In some cases you may need to give the Red5 Pro server a little help by “forcing” these IP assignments. To do so, modify the {red5pro}/conf/webrtc-plugin.properties file. Uncomment the following lines and modify them with your server’s public and private IP addresses.

Modify red5pro/conf/webrtc-plugin.properties, replacing yourpublic.ip.address.here and local.private.ip.address.here with the server’s public and private IP addresses, respectively.

 # Forcing a public IP address
 #force.public.ip=yourpublic.ip.address.here

 # Forcing a private IP address
 #force.local.ip=local.private.ip.address.here

If you are still having ICE failures, you may also need to enable port availability checking by uncommenting:

# Configure port availability checking

Safari browser develop, WebRTC options include Allow Media Capture on Insecure Sites which will enable publish/subscribe testing without SSL.