Step 1: First you’ll need to go to the DedicatedMC.io Panel and select the server of which you want to allow multiple Minecraft Versions on.
Step 2: In the selected server, either go to ‘File Management’ or use your choice for SFTP. A guide on how to use SFTP can be found here.
Step 3: When using the File Manager on the Panel or SFTP, navigate inside the /plugins folder.
Step 4: Download the correct version of ProtocolSupport to support multiple client versions on your server.
Step 5: In your File Manager, upload ProtocolSupport to the /plugins folder by clicking Upload on the Panel, or dragging the Jar File into your SFTP Client.
Step 6: Your Server now supports Multiple Versions! You will need to restart your Minecraft Server to reload your plugins! Do /pl to see if the plugin was successfully installed and is not outdated!