In app Element Call gets stuck on all participants _Waiting for Media..._

[lampholder]

Steps to reproduce

1. Go to a room with a call already in progress (by clicking the toast notif if there is one, or just going straight there)
2. Click 'join'
3. See lots of Waiting for media rectangles. This never resolves.

Outcome

What did you expect?

What happened instead?

Operating system

macOS

Browser information

Firefox nightly 144.0a1 (2025-09-07) (aarch64)

URL for webapp

develop.element.io

Application version

Element version: cd7f1a0638b4-js-82aa04d894d7 Crypto version: Rust SDK 0.13.0 (f64839e), Vodozemac 0.9.0

Homeserver

lant.uk

Will you send logs?

Yes

[lampholder]

My .well-known/matrix/client looks like this:

{
    "m.homeserver": {
        "base_url": "https://matrix.lant.uk"
    },
    "org.matrix.msc4143.rtc_foci": [
        {
            "type": "livekit",
            "livekit_service_url": "https://livekit-jwt.call.matrix.org"
        }
    ]
}

[lampholder]

Was the capability to use livekit-jwt.call.matrix.org removed? The blog warns that it might go away after May 5th.

If so, then I guess this issue is more "can we have a better error message for that case" please :)

[fkwp]

❯ ./test_matrix.py lant.uk
Testing server lant.uk
  Federation url: https://matrix.lant.uk:8448
✔ Server well-known exists
𐄂 Client well-known has no CORS header
  Client url: https://matrix.lant.uk
  Adding livekit service URL: https://livekit-jwt.call.matrix.org
✔ Server version: Synapse (1.134.0)
✔ Federation API endpoints seem to work fine
✔ Client API endpoints seem to work fine
✔ MatrixRTC SFU configured
  JWTauth healtz url: https://livekit-jwt.call.matrix.org
  jwt has no CORS header (that is OK)
✔ JWTauth responds
✔ jwt /sfu/get without auth returns (405). This is good!
  jwt: no credentials passed, not trying authed requests
𐄂 MatrixRTC configured but delayed events turned off (MSC4140). BAD!
  No room summaries (MSC3266) (unstable) support (?)
✔ Direct registration and guest access forbidden per se 👍

[fkwp]

I guess the CORS headers are the problem here