WebRTC browser-to-browser connections fail in github version (deployed or local `yarn dev`) but work in official, deployed app

[yeus]

Commit / version: 0254d9602a89492ae61bffa9ae3e41bb7ff7a493

Description:
I’m generally able to establish WebRTC connections using the Universal Connectivity app, but only when using the official deployed app at:
https://universal-connectivity.on-fleek.app/

When running the app locally using yarn dev, direct browser-to-browser WebRTC connections fail. The different instances discover each other though and can also exchange messages.

What works:

• WebRTC connection: Official App → Dev App ✅
• WebRTC connection: Official App → Official App ✅

What doesn’t work:

• WebRTC connection: Dev App → Local App ❌

I tested this under different local networks, both online and offline — results are consistent. I also deployed my own version of the app online (using the same p2p-code as the official version ) and getting the same error.

What I don't understand is why this works only in the deployed version, but not in the github version. I tried deploying it to my own https. domain and it doesn't work there either I am getting the same errors there as in local dev version.

---

Suspected cause:
From my debugging, it seems the failure might be related to the inability to negotiate /webrtc-signaling/0.0.1 in the github version of the universal connectivity demo. This likely prevents proper SDP exchange for WebRTC.

Relevant error log (excerpt):

libp2p:discovery:pubsub discovered peer 12D3KooWGqVLhqqyvhLiWW9KfM5vgFbJim1QWrEAQLEsZtLQ1NNf on universal-connectivity-browser-peer-discovery +7s

10:56:33.701 ui:libp2p dialling WebRTC multiaddrs: [...]

10:56:33.741 libp2p:websockets:connection:outbound:... error could not create new outbound stream on connection to /ip4/147.28.186.157/tcp/9095/tls/sni/... for protocols /webrtc-signaling/0.0.1 - UnsupportedProtocolError: protocol selection failed

Full attached console log shows this error consistently when attempting Local App → Local App WebRTC connections.

console_output.txt

---

Steps to reproduce:

1. Clone the repo at commit 0254d9602a89492ae61bffa9ae3e41bb7ff7a493.
2. Run yarn install.
3. Run yarn dev.
4. Open two browser windows (or different devices) pointing to the local app.
5. Attempt to establish a WebRTC connection between them.

Expected result:
Direct browser-to-browser WebRTC connection established.

Actual result:
Fails with UnsupportedProtocolError: protocol selection failed.

---

Additional notes:
This issue does not occur in the deployed app. This suggests there may be differences in how signaling is handled locally vs. in production — I don't know what it could be as I am using the same relay as the deployed version. different instances/peers are able discover & talk to each other etc.. Just the webrtc connections don't work..

console_output.txt

[yeus]

I am realizing this might be due to a version mismatch. I did yarn install without taking package-lock.json into account! if I do npm update, the universal connectivity app fails as well..

this results in the following dependencies:

├── @chainsafe/libp2p-gossipsub@14.1.1
├── @chainsafe/libp2p-yamux@7.0.4
├── @libp2p/webrtc@5.2.24
├── @libp2p/websockets@9.2.19
└── libp2p@2.10.0

and that

vs frmo package-json.lock

npm ls libp2p @libp2p/webrtc @libp2p/webrtc-direct @libp2p/websockets @chainsafe/libp2p-gossipsub @chainsafe/libp2p-yamux
universal-connectivity-browser@ /home/tom/git/universal-connectivity/js-peer
├── @chainsafe/libp2p-gossipsub@14.1.0
├── @chainsafe/libp2p-yamux@7.0.1
├── @libp2p/webrtc@5.2.5
├── @libp2p/websockets@9.2.3
└── libp2p@2.7.4

so when doing that, the multi address received here:

universal-connectivity/js-peer/src/lib/libp2p.ts

Lines 97 to 107 in 227825f

	// 👇 explicitly dial peers discovered via pubsub
	libp2p.addEventListener('peer:discovery', (event) => {
	const { multiaddrs, id } = event.detail
	if (libp2p.getConnections(id)?.length > 0) {
	log(`Already connected to peer %s. Will not try dialling`, id)
	return
	}
	dialWebRTCMaddrs(libp2p, multiaddrs)
	})

doesn't include the peer ID and then the error happens, I guess?

one question I have is: how does libp2p prevent version mismatches and other things? how can I prevent that? Can we regard universal-connectivity as a "reference" which versions to use in order to make it work?

where do we report errors related to that?

[NiKrause]

there's no dcutr in side https://github.com/libp2p/universal-connectivity/blob/main/js-peer/package.json how come? Isn't dcutr necessary for webrtc between browsers?