Connection problems

Walk through the section that matches your symptom.

”Connection refused”

The server is not running, or the port is wrong.

Verify the address is correct. Default port is 64738.
Ping the host:
Terminal window
```
ping your-host
```
Test the port:
Terminal window
```
nc -zv your-host 64738
```
If this fails, the firewall is in the way.
(Server side) Confirm the container is running:
Terminal window
```
docker compose ps
```

“Connection timed out”

The packet is being dropped somewhere between you and the server.

Verify with another network (phone tether) to rule out your local ISP.
(Server side) Check the firewall lets in 64738/tcp and 64738/udp.
(Server side) Check the cloud provider’s security group allows the same ports.
Force TCP in audio settings, sometimes only UDP is blocked.

”TLS handshake failed”

The server’s certificate is rejected by your client.

The server’s certificate may have changed. The app asks you to accept the new identity. Read the new hash carefully before accepting.
If you used to connect and the server has been reinstalled, the hash is expected to change. Accept it.

”Wrong username or password”

Server has a password set. Get it from the admin.
The username does not match the case (Mumble is case-insensitive for registered users, but case-sensitive for the initial login).
Your certificate is wrong for the registered name. Open Identities and confirm you are using the right one.

”Server rejected the username regex”

The server requires usernames to match a pattern.

Use 3 to 15 characters of letters, digits, dashes, underscores by default.
The admin can change MUMBLE_CONFIG_USERNAME to a different regex.

”Disconnects randomly after a few minutes”

Often a NAT timeout or a packet-loss spike.

Turn on Auto-reconnect in Advanced settings.
Force TCP to keep one connection alive.
(Server side) Check for keepalive settings in the server INI.
(Server side) Confirm the cloud provider does not have an idle timeout on the load balancer below 60 seconds.

”Connects but cannot hear anyone or be heard”

Voice (UDP) is broken even though the control channel (TCP) works.

Turn on Force TCP in audio settings. This is the universal fix; you trade a little latency for reliability.
(Server side) Open UDP 64738 in the firewall and forwarder.

”The app shows me as connecting forever”

Stuck in the bootstrap phase. The first connect after start fetches channels, users, and own session info.

Restart the app.
Look at the Activity log for an error.
If you self-hosted, look at the server logs.

”Public server list is empty”

Your internet route to mumble.info’s directory is blocked. Try again later.
Some corporate networks block the directory.

”Cannot find my self-hosted server in the public list”

You did not set registerName, registerHostname, and registerPassword in the server config.
The directory has not yet picked up your server. Can take up to an hour.

”App says certificate cannot be verified”

This is the trust-on-first-use warning. The first time you connect the app pins the server’s certificate hash. If it ever changes, you get this warning.

If you trust the change, accept.
If you did not expect a change, stop. The connection might be intercepted.

Server-side: connection refused with no logs

Check docker compose logs mumble-server for a panic at startup.
The most common cause is a typo in MUMBLE_CONFIG_*. The server refuses to start with an unknown key by default.
Set MUMBLE_ACCEPT_UNKNOWN_SETTINGS=true to pass through unknown values (use sparingly, you might hide a real typo).

Still broken?

Open a bug report with:

Whether you can nc -zv the port.
Whether the issue happens from a different network.
Debug logs from both the client and the server.