Rust+ Companion App on a Server: app.port, app.publicip and Pairing Fixes
Rust+ lets players use the companion phone app with your server. For it to work, the server runs a small companion service on its own TCP port, and the app has to be able to reach that port from the internet. Most Rust+ problems on a hosted server are port or address problems, not settings you have missed.
This guide explains how the port is chosen, the variables that control it, how to check what the server is using, and the rules that protect pairing. It was checked on 2026-11-15 against Facepunch's own Rust+ companion server documentation. On ChicagoServers the ports are assigned by the panel, so some of this is for understanding and diagnosing rather than editing.
- The default companion port is the game port plus 67, or the RCON port plus 67, whichever is larger. With unchanged ports that is 28082.
- Run
app.infoon the Console tab to see the port and connection settings in use. app.portmust be 10000 or higher, and changing it needs a restart.- If the app connects to the wrong address,
app.publicipis the setting that corrects it. - Never share, copy or delete companion.id. Doing so can break notifications for all your players and force re-pairing.
On this page
How Rust+ reaches your server
Rust+ does not use the game port. The server opens a separate companion port, and the app connects to it over TCP. Facepunch says that for most setups the only requirement is that this TCP port is reachable from the internet, which means forwarded, open and allowed through any firewall. The server also has to be able to reach Facepunch's companion service, which it uses to register and to send push notifications.
Variables
| Variable | What it does |
|---|---|
app.port | Sets the companion port. Must be 10000 or higher to be reached by the Rust+ backend. A restart is required. |
app.publicip | Set this to the correct address if the IP the app connects to is wrong. |
app.listenip | For complex networks where you must choose the network interface to listen on. Facepunch says to set it to the server's public IP. |
app.id | Must not be changed. |
The default port is calculated, not fixed. It is the game port plus 67, or the RCON port plus 67, whichever result is larger. With default ports that works out to 28082. Because the panel assigns your ports, yours will differ. Run app.info to read the real value instead of calculating it.
Check that it works
- Run app.info
Open the Console tab and run the command. Note the port, and the address it reports.
app.info - Look in the log
If the server's own connectivity test fails, the log shows a message that the Rust+ companion server connectivity test failed and that Rust+ features are disabled. Rust+ is then turned off automatically.
- Pair in the app
Pair with the server from the Rust+ app. Facepunch also describes testing the port with a WebSocket client pointed at the server address and companion port.
Rules that protect pairing
Facepunch warns that breaking these rules can disable notification permission for all players and may require everyone to pair again:
- Do not share
companion.id, or use another server's copy of it. - Do not use one file on several servers.
- Do not delete it casually. Deleting it creates a new identity, and the old one cannot be recovered.
- Do not change
app.id. - Keep
companion.idwith your server and with its backups. See the backup guide and the wipe guide before deleting files.
Common problems
| Problem | Likely cause and fix |
|---|---|
| Rust+ features are disabled in the log | The connectivity test failed. Check that the companion TCP port is reachable and at least 10000. |
| The app cannot connect | Port closed, or the app is given the wrong address. Run app.info and compare it with the address you expect. |
| Wrong IP shown to the app | Set app.publicip to the right address, or ask support. |
| Port below 10000 | The connectivity check does not work below 10000. Use a higher port. |
| Notifications stopped for everyone | The companion.id file was shared, replaced or deleted. Players may need to pair again. |
| Changed the port but nothing happened | Restart the server. A restart is required. |
Frequently asked questions
What port does Rust+ use?
A separate TCP companion port. By default it is the game port plus 67 or the RCON port plus 67, whichever is larger, which is 28082 with default ports.
How do I check my Rust+ port?
Run app.info on the server console. It shows the port and connection settings in use.
What is the minimum Rust+ app.port?
10000. Facepunch says lower ports will not be reached by the Rust+ backend, and the connectivity check fails below it.
Why does Rust+ say it is disabled on my server?
The server's connectivity test failed, so Rust+ was disabled automatically. Make sure the companion TCP port is reachable from the internet.
Can I delete companion.id?
Avoid it. Deleting it creates a new identity that cannot be undone, and can stop notifications for all players until they pair again.