Once a month (sometimes more often) Rust developers update their game. When a new patch appears, it's usually necessary to update the server and even Oxide if you have mods/plugins on your server.
If you experience issues while connecting to your server or suddenly cannot see your server on the server list, the first thing to try, before anything else, is performing these updates, if the issues weren't present before.
To update your Rust server and even Oxide/uMod, follow these steps:
1. Login to PonyGaming gamepanel
2. Stop your server
3. Go to File manager (menu)
4. Right click on Steamapps folder and delete it
5. Click on Steam update (menu) and confirm it (if you have uMod/Oxide installed, it updates it automatically)
6. Wait for update to be finished
7. Start your server again
And it's done. Your Rust server should be updated now and ready to use.