As mentioned, you cant manually set up your listening ports - this is handled internally by ICE, which needs to connect to a STUN server to get (at a minimum) your public IP address.

edit: cant reply to your comment fulafel, but on that project you posted: https://github.com/cjb/serverless-webrtc/blob/master/serverl... Also, note that even if this wasnt defined, some browsers contain defaults. You 100% need STUN, but you can handle the signalling manually - as I stated.

edit2: cant reply to your comment ibc, but I was explaining the bare minimum 'serverless' webrtc case still required a STUN server. I appreciate that mediasoup SFU uses ice-lite instead.

I know I've seen at least data channel working without STUN, this was the demo I think: https://github.com/cjb/serverless-webrtc/

If you say it's different with media channels, I'll believe you.

WebRTC can tell you your ip address without any external server, that only breaks if you are dealing with NAT.

edit: to clarify the NAT-less use case, i'm thinking of apps that can rely on/require p2p supporting IPv6 connectivity.

And somehow this discussion become a general topic about WebRTC scenarios. They do exist, yes, but mediasoup is a SFU scenario. No STUN is required at all. TURN may be needed if the client network/router blocks UDP.

Re your edit, ok i stand corrected, thanks for the correction!