Serial Console gives you access to your server, even if it is no longer accessible via the network. The Serial Console is only for 1&1 Dedicated Server Linux and 1&1 Dedicated Server Windows. For a 1&1 Dynamic Cloud Server, you must use the VNC Remote Console instead. 1&1 Virtual Server uses Virtuozzo for most troubleshooting.
Serial Console is used when you cannot gain network access to your server. Serial Console access is gained by logging into a specific machine in our data centre via SSH, using the username and password provided in the Serial Console section of your 1&1 Control Panel. A connection via the serial port is made to your specific server. This give you command line access to make necessary changes in order to regain access to your server via the network.