If you login and are kicked with "Disconnected" immediately
Upon login, if you receive "Disconnected" then your backend is most likely unreachable.
Your server is not running on the IP and port specified on the panel
The IP and port on the panel is incorrect to what is defined on the panel
The IP address we are proxying to is non-routable from our network
Firstly, it is a good idea to determine if your server is reachable from the outside world. From a server that is not the one running your Bungee/Spigot, verify that it can actually connect to your server. We can do this using a tool call netcat.
apt-get install netcat -y
yum install netcat -y
Run the following command, with the IP and port replaced as necessary.
nc -v IP PORT -w 3
If you see 25565 (?) open in the output, then your server is listening on the port, but might be hanging and not accepting normal MC connections. If this is the case, remove the TCPShield plugin and ensure you can login to the raw IP and port from your client directly. If this works, check your dashboard to ensure your backend IP and port are correct.
If you see Connection refused in the output, then our proxies can properly route to your backend IP, but your Minecraft server is not running on the defined port in your dashboard. Ensure these both match and/or update as necessary. Additionally, ensure your listening IP is correct in your server.properties if you are running Spigot, or config.yml if you are running Bungee.
If you see Connection timed out in the output, then our proxies cannot properly route to your backend IP address. Check your server-sided firewall to ensure the backend port defined in your dashboard is open to the outside world. You may need to consult your hosting provider if modifying the server-side firewall does not work (for example, your IP address might not be bound properly to your machine).
If everything is configured properly, netcat should return the following output, and you should be able to login normally via the Minecraft client.
$ nc -v 126.96.36.199 25565 -w 3
ip10.ip-51-161-99.net [188.8.131.52] 25565 (?) open