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---
title: "Self-hosting Matrix + Element Call with LiveKit: from zero to working (and the [not so!!] fun debugging along the way)"
date: 2025-08-26
tags: ["matrix", "synapse", "element-call", "livekit", "coturn", "nginx", "webrtc", "self-hosting", "debugging"]
draft: false
description: "How I set up a Matrix homeserver (Synapse) with TURN and Element Call using LiveKit, plus the exact debugging steps that took it from 'waiting for media' to solid calls."
cover:
image: "/images/matrix-cover.png"
alt: "Matrix, Signal but distributed"
caption: "Distributed end-to-end encrypted chat platform"
relative: true
hidden: false
---
> TL;DR: The call kept saying **“waiting for media”** because the browser never opened a WebSocket to LiveKit. The root cause was **duplicate `Access-Control-Allow-Origin` headers** on `/sfu/get` (CORS), which stopped the JWT response. Fixing CORS and ensuring the WS proxy worked (HTTP **101** in logs) solved it.
## What I'm building
- A **Matrix homeserver** (Synapse) at `matrix.example.com` (replace with your domain).
- **TURN/STUN** (coTURN) for NAT traversal.
- **Element Call** backed by **LiveKit**, fronted by `rtc.example.com`.
- **Nginx (host)** as the single reverse proxy for everything.
- **Cloudflare** DNS (with `rtc.*` set to **DNS-only**, no orange cloud).
- **UFW** firewall opened for Matrix federation, TURN, and LiveKit media ports.
> I used Docker for Synapse, PostgreSQL, LiveKit and the JWT helper. I used **host** Nginx (not Nginx in Docker) to avoid port binding conflicts on 80/443/8448.
---
## Prereqs
- DNS A/AAAA:
- `matrix.example.com` → your server (v4/v6)
- `rtc.example.com` → your server (v4/v6)
- Certificates:
- `matrix.example.com` and `rtc.example.com` via Lets Encrypt on the host
- Cloudflare: **DNS-only (grey cloud)** for `rtc.example.com` so WebSockets & UDP work without interference.
- UFW / firewall open:
- 80/tcp, 443/tcp
- 8448/tcp (Matrix federation)
- 3478/tcp, 3478/udp and **5349/tcp** (TURN/TLS)
- **LiveKit**: 7881/tcp and **5010050200/udp** (or your chosen range)
- Docker + docker compose installed.
---
## Synapse + PostgreSQL
### 1) The PostgreSQL collation gotcha
Synapse prefers the database collation **`C`**. If your Postgres cluster was initialized with `en_US.utf8`, Synapse will error like:
```
Database has incorrect collation of 'en_US.utf8'. Should be 'C'
```
**Two ways to resolve:**
- **Preferred (clean)**: Re-initialize the Postgres **cluster** with `C` and `UTF-8`:
```yaml
# docker-compose.yml (excerpt for Postgres)
services:
db:
image: postgres:16
environment:
POSTGRES_DB: synapse
POSTGRES_USER: synapse
POSTGRES_PASSWORD: <strong-password>
POSTGRES_INITDB_ARGS: "--locale=C --encoding=UTF8 --lc-collate=C --lc-ctype=C"
volumes:
- ./pgdata:/var/lib/postgresql/data
```
> Requires wiping the volume and recreating the DB.
- **Pragmatic (works quickly)**: In Synapses DB config, set `allow_unsafe_locale: true`. This bypasses the check. Its fine for hobby use; for production, prefer the clean `C` cluster.
### 2) Start Synapse and generate config
```bash
docker compose up -d db synapse
# Logs
docker compose logs --tail=200 synapse
```
Ensure Synapse prints your **server_name** and **public base URL** and stays up.
### 3) Create an admin user
```bash
# Exec into the running Synapse container:
docker compose exec synapse register_new_matrix_user \
-c /data/homeserver.yaml -u <username> -p <password> \
-a -k
```
> If you see “Unknown execution mode”, you probably ran the binary with the wrong entrypoint. Use `docker compose exec synapse …` against the running container.
---
## TURN (coTURN)
### 1) Avoid bad inline comments
If you see errors like:
```
ERROR: Unknown boolean value: # log to journald/syslog. You can use on/off, yes/no, 1/0, true/false.
```
…it means a `#` comment is on the **same line** as a boolean directive. Move comments to their own lines.
### 2) Minimal `turnserver.conf`
```ini
listening-port=3478
tls-listening-port=5349
fingerprint
use-auth-secret
static-auth-secret=<shared-secret> # also set in Synapse
realm=example.com # used in creds generation
total-quota=0
bps-capacity=0
cli-password=<admin-pass>
no-cli
cert=/etc/letsencrypt/live/turn.example.com/fullchain.pem
pkey=/etc/letsencrypt/live/turn.example.com/privkey.pem
# If behind NAT:
# external-ip=<public-ip>/<internal-ip>
```
### 3) Wire TURN into Synapse
In `homeserver.yaml`:
```yaml
turn_uris:
- "turn:turn.example.com?transport=udp"
- "turn:turn.example.com?transport=tcp"
- "turns:turn.example.com:5349?transport=tcp"
turn_shared_secret: "<shared-secret>"
turn_user_lifetime: "1d"
```
Verify the homeserver issues TURN creds:
```bash
TOKEN='<your matrix access token>'
curl -s -H "Authorization: Bearer $TOKEN" \
https://matrix.example.com/_matrix/client/v3/voip/turnServer | jq
```
You should see `uris`, a time-limited `username` and `password`.
---
## Nginx (host) for Synapse and federation
Create `/etc/nginx/conf.d/matrix.conf`:
```nginx
# Client traffic on 443
server {
listen 443 ssl; listen [::]:443 ssl;
server_name matrix.example.com;
ssl_certificate /etc/letsencrypt/live/matrix.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/matrix.example.com/privkey.pem;
# Proxy client & admin APIs to Synapse (container) on 8008
location ~ ^(/_matrix|/_synapse/client) {
proxy_pass http://127.0.0.1:8008;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $host;
client_max_body_size 50M;
}
# Advertise homeserver base + RTC focus (MSC4143) via .well-known
location = /.well-known/matrix/client {
default_type application/json;
add_header Access-Control-Allow-Origin "*" always;
return 200 '{"m.homeserver":{"base_url":"https://matrix.example.com"},"org.matrix.msc4143.rtc_foci":[{"type":"livekit","livekit_service_url":"https://rtc.example.com"}]}';
}
}
# Federation on 8448
server {
listen 8448 ssl http2; listen [::]:8448 ssl http2;
server_name matrix.example.com;
ssl_certificate /etc/letsencrypt/live/matrix.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/matrix.example.com/privkey.pem;
location / {
proxy_pass http://127.0.0.1:8008;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $host;
client_max_body_size 50M;
}
}
```
Reload and sanity check:
```bash
sudo nginx -t && sudo systemctl reload nginx
curl -s https://matrix.example.com/.well-known/matrix/client | jq
```
Also check Synapse supports RTC signaling (MSC4140) so clients actually use it:
```bash
curl -s https://matrix.example.com/_matrix/client/versions | jq '.unstable_features."org.matrix.msc4140"'
# expect: true
```
---
## Element Call + LiveKit
Ill run **LiveKit** and the small **JWT helper** (Elements `elementcall_jwt`) in Docker. LiveKit handles media; the JWT helper mints access tokens for WebSocket connects.
### 1) LiveKit config (`/etc/livekit.yaml` inside container)
```yaml
port: 7880
bind_addresses: ["0.0.0.0"]
rtc:
tcp_port: 7881
port_range_start: 50100
port_range_end: 50200
use_external_ip: true
logging:
level: info
turn:
enabled: false
keys:
lk_prod_1: "REPLACE_WITH_A_64_CHAR_RANDOM_SECRET___________________________________"
```
> **Important:** the secret must be **>= 32 chars**. The default `devkey` will trigger `secret is too short` warnings and wont work with the JWT helper.
### 2) elementcall_jwt env
Run it with:
- `LIVEKIT_URL=wss://rtc.example.com` _(root WS URL, **no** `/livekit/sfu` path)_
- `LIVEKIT_KEY=lk_prod_1`
- `LIVEKIT_SECRET=<the long secret above>`
- `LIVEKIT_JWT_PORT=8080` (internal HTTP port the proxy will hit)
- Optionally: `LIVEKIT_FULL_ACCESS_HOMESERVERS=*` during setup
Check logs on start; it prints the LIVEKIT_URL it will advertise.
### 3) Nginx (host) for `rtc.example.com`
Create `/etc/nginx/conf.d/rtc.conf`:
```nginx
server {
listen 443 ssl; listen [::]:443 ssl;
server_name rtc.example.com;
ssl_certificate /etc/letsencrypt/live/rtc.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/rtc.example.com/privkey.pem;
access_log /var/log/nginx/rtc.access.log combined;
# 3a) JWT endpoint with clean CORS (avoid duplicate ACAO)
location = /sfu/get {
proxy_hide_header Access-Control-Allow-Origin;
add_header Access-Control-Allow-Origin $http_origin always;
add_header Vary "Origin" always;
add_header Access-Control-Allow-Methods "POST, OPTIONS" always;
add_header Access-Control-Allow-Headers "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization" always;
if ($request_method = OPTIONS) { return 204; }
proxy_set_header Host $host;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_pass http://127.0.0.1:8070/sfu/get; # elementcall_jwt
}
# 3b) LiveKit WS & HTTP (catch-all)
location / {
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Sec-WebSocket-Protocol $http_sec_websocket_protocol; # "livekit"
proxy_set_header Origin $http_origin;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_buffering off;
proxy_read_timeout 3600s;
proxy_pass http://127.0.0.1:7880; # livekit
}
}
```
Reload and basic checks:
```bash
sudo nginx -t && sudo systemctl reload nginx
# JWT preflight (should return a single ACAO header)
curl -si -X OPTIONS https://rtc.example.com/sfu/get \
-H 'Origin: https://app.element.io' \
-H 'Access-Control-Request-Method: POST' \
-H 'Access-Control-Request-Headers: authorization, content-type' | sed -n '1,30p'
# Expected: one Access-Control-Allow-Origin and 200/204
```
> **Why I did this:** I initially had **two** `Access-Control-Allow-Origin` headers (one added by the upstream, one by Nginx). Browsers reject that with “Access-Control-Allow-Origin cannot contain more than one origin”, so the JWT response never reached the client. Fixing CORS fixed everything.
---
## The “waiting for media” debugging story (how I found it)
Symptom: Element Call created rooms, but calls stayed on **“waiting for media.”**
What worked:
- `elementcall_jwt` could **CreateRoom** in LiveKit (seen in logs).
- TURN creds endpoint returned time-limited credentials.
What didnt appear:
- No **HTTP 101** lines in `rtc.access.log` → the **browser never established a WebSocket** to LiveKit.
### Step 1: prove the WS vhost works (even without auth)
```bash
curl -v --http1.1 \
-H 'Connection: Upgrade' -H 'Upgrade: websocket' \
-H 'Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==' \
-H 'Sec-WebSocket-Version: 13' \
https://rtc.example.com/rtc -o /dev/null
```
Result: I got a `401` (expected), but importantly I saw a log line in `rtc.access.log`. So **Nginx WS proxying was fine**.
### Step 2: check the browser console
The smoking gun in DevTools:
```
Access-Control-Allow-Origin cannot contain more than one origin.
Fetch API cannot load https://rtc.example.com/sfu/get due to access control checks.
```
The browser refused the JWT call due to duplicated **ACAO** headers, so no token → no WebSocket connect.
**Fix:** in Nginx I added:
```nginx
proxy_hide_header Access-Control-Allow-Origin;
add_header Access-Control-Allow-Origin $http_origin always;
add_header Vary "Origin" always;
```
…and ensured no other `add_header` created duplicates. After that, `/sfu/get` succeeded and the WebSocket to `wss://rtc.example.com` immediately followed (I saw **HTTP 101** in the logs).
### Step 3: confirm LiveKit side
Once the WS was up, LiveKit logs showed participants joining (not just `RoomService.CreateRoom`), and calls were established.
---
## Useful verification commands
```bash
# Synapse features (expect MSC4140 true)
curl -s https://matrix.example.com/_matrix/client/versions | jq '.unstable_features."org.matrix.msc4140"'
# Well-known with RTC focus
curl -s https://matrix.example.com/.well-known/matrix/client | jq
# TURN creds (with your access token)
curl -s -H "Authorization: Bearer $TOKEN" \
https://matrix.example.com/_matrix/client/v3/voip/turnServer | jq
# JWT health
curl -si -X POST https://rtc.example.com/sfu/get
# LiveKit simple HTTP probe
curl -si https://rtc.example.com | head
# Nginx logs (look for 101 Switching Protocols when a call starts)
sudo tail -f /var/log/nginx/rtc.access.log | grep ' 101 '
```
---
## Common pitfalls (I hit these so you dont have to)
- **Host Nginx vs Docker Nginx:** If you already run Nginx on the host, dont also bind 80/443/8448 in a Docker Nginx — youll get `bind() ... already in use` and restart loops. Use **host** Nginx to reverse proxy to containers.
- **Nginx `http2` directive:** Old Nginx may not support the `http2` directive on `listen`. Use `listen 443 ssl;` (and add `http2` if your version supports it).
- **Certificate name mismatch:** Make sure `rtc.example.com`s vhost uses a certificate **for that exact hostname** (initially I had the `matrix.*` cert on `rtc.*` and curl complained).
- **Postgres collation:** Either initialize the cluster with `C` or use `allow_unsafe_locale: true` in Synapse DB config to get running quickly.
- **CORS duplication on `/sfu/get`:** Only ONE `Access-Control-Allow-Origin` header. If the upstream adds it too, use `proxy_hide_header Access-Control-Allow-Origin;` on the Nginx location.
- **Cloudflare:** Use **DNS-only** for `rtc.*`. Proxies can interfere with WS and UDP paths.
- **Firewall:** Open the LiveKit UDP range and TURN ports on both v4 and v6.
---
## Final checklist (print me)
- [ ] `https://matrix.example.com/.well-known/matrix/client` returns **both** `m.homeserver.base_url` and `org.matrix.msc4143.rtc_foci` pointing to `https://rtc.example.com`.
- [ ] `/_matrix/client/versions` shows `"org.matrix.msc4140": true`.
- [ ] `/sfu/get` **preflight** returns **one** `Access-Control-Allow-Origin` and **200/204**.
- [ ] Starting a call creates **HTTP 101** entries to `wss://rtc.example.com` in `rtc.access.log`.
- [ ] LiveKit logs show **participants joining** (not just CreateRoom).
- [ ] `/voip/turnServer` returns time-limited TURN credentials.
- [ ] Cloudflare set to **DNS-only** for `rtc.*`. UFW allows 7881/tcp and your LiveKit UDP range.
---
### Credits & tooling
- Matrix Synapse, coTURN, LiveKit, Element Call.
- `curl`, `jq`, `docker compose logs`, Nginx access logs. These are your best friends.
- The debugging breakthrough was catching CORS errors in the browser console and looking for **HTTP 101** in Nginx logs.
Happy calling! 🎉
---
{{< sigdl >}}