1-1 voip call fails even when `turn.matrix.org` fallback is enabled

### Steps to reproduce

Setup:
- Person A using a custom homeserver (https://tedomum.net) _with no configured TURN relays_,
- Person B using the `matrix.org` homeserver

1. Both persons go in the audio&video settings and:
- enable the `turn.matrix.org` relay fallback,
- disable p2p
2. A 1-1 audio call is started by either person (it can be A or B, it makes no difference)
3. The other person accepts the call

### Outcome

#### What did you expect?

The call starts using the `turn.matrix.org` relay and works well.

#### What happened instead?

The call never starts and is stuck in a _Connecting_ state, with no error message displayed. The only choice is to cancel the call.

### Operating system

Person A : Linux (Fedora 36) ; Person B : MacOS

### Application version

Element : 1.11.8

### How did you install the app?

Flatpak

### Homeserver

https://tedomum.net

### Will you send logs?

No