Thanks — I see the error you're hitting: "could not establish signal connection: Failed to construct 'RTCPeerConnection': ICE server parsing failed: Invalid hostname format." I’ll walk you through the most likely causes and concrete checks you can do to resolve it. What this means • The browser rejected the ICE server list passed to

RTCPeerConnection

because one or more ICE server URIs have an invalid hostname or format. • The ICE servers can come from your LiveKit server (returned with token/grants) or from client-side RTC config (e.g.,

connectOpts.rtcConfig

) if you set that manually. Steps to diagnose and fix 1. Inspect the ICE server URLs your client receives ◦ In the browser console, log the RTC configuration/ICE servers right before you call connect or construct

RTCPeerConnection

. Look for entries like

stun:...

or

turn:...

. ◦ Confirm each URL uses a proper scheme and hostname, for example: ▪︎

stun:stun.l.google.com:19302

▪︎

turn:turn.example.com:443?transport=tcp

◦ Invalid examples that cause this error: missing scheme (

turn.example.com

), malformed port (

turn:host:badport

), or spaces/illegal characters. 1. If self-hosted LiveKit is providing ICE servers, check server config ◦ Verify your

livekit.yaml

(or wherever you configure TURN/STUN) contains valid, fully qualified hostnames or IPs with correct URL format. ◦ Ensure environment variables like

LIVEKIT_URL

are set to a valid URL (e.g.,

wss://your-livekit.example.com

) and not a malformed string. 1. If you’re manually passing

rtcConfig

from the client ◦ Validate the

iceServers

array you pass: each entry should have a

urls

field with correctly formatted URIs (string or array of strings). ◦ Example shape:

{
       iceServers: [
         { urls: ["stun:stun.l.google.com:19302"] },
         { urls: ["turn:turn.example.com:443?transport=tcp"], username: "user", credential: "pass" }
       ]
     }

1. Common mistakes to look for ◦ Using an IP without scheme (should be

stun:1.2.3.4:3478

). ◦ Including credentials incorrectly (should be separate `username`/`credential` fields or

turn:host?transport=...

). ◦ Trailing slashes, spaces, or other illegal characters in hostnames. ◦ Returning non-URL strings in the ICE server list (e.g., plain hostnames). 1. Network / DNS checks ◦ Confirm the hostname resolves from the client environment (DNS lookup or ping). ◦ Ensure firewalls allow the relevant ports (TURN/STUN typically 3478/5349 or the ports your TURN server uses). If you want, please share (redact credentials) one of the ICE server entries you see in the browser console or a snippet of how you configure

iceServers

/

livekit.yaml

. With that I can point out the exact formatting issue and suggest the minimal change to fix it. Sources: Firewall Tips for LiveKit Connectivity | LiveKit | server-sdk-js | livekit/livekit_composite | DeepWiki | Self-hosted deployments | LiveKit Documentation | Diagnosing Connection Errors with the Connection Test Utility | LiveKit | Configure ZScaler proxy for LiveKit connections | LiveKit, with interactive elements