Matrix Chat: open it, first login, settings, fixes

Published 11 May 2026 · Updated 18 September 2026 · SparkBox team

Run your own private chat server with Matrix Synapse and the Element web client. End-to-end encrypted, federated, and Signal-compatible via bridges. A self-hosted alternative to Signal, WhatsApp, and Slack. This is the short card for it — the two minutes after you press Enable, and the page to come back to when something is off.

Before you turn it on

First run generates homeserver.yaml config. Register admin user after startup via docker exec.

Open it

Dashboard → Apps → Matrix Chat → Open. The direct address on your network is:

http://<your-box-IP>:8448

Create an admin via SparkBox Settings first, then sign in on Element.

First login

Matrix Synapse doesn't show a setup UI — you create admin users from the command line. SSH into your box and run `sudo docker exec -it sb-synapse register_new_matrix_user -c /data/homeserver.yaml http://localhost:8008` — it'll prompt for a username and password and ask 'Make admin? yes'. Then sign in on Element with that username.

Any password the installer generated for you is under Settings → Passwords; the Open button offers to copy it.

Settings that matter

Change these under Apps → Matrix Chat (or when you enable it):

• Matrix Server Name — The server name (domain) for your Matrix homeserver

When it breaks

If it will not open, check the app card first — a red dot means it is restarting or unhealthy, and this walkthrough reads the reason from its log. Tom AI on the dashboard can do the same for you.

Where your data lives

/opt/sparkbox/modules/matrix/config/

Included in the dashboard's Backup by default. Restoring that backup on a fresh install brings Matrix Chat back exactly as it was.