ReadyNAS 516 no longer supported?



I have a ReadyNAS 516. I updated the firmware last night and then updated to the latest version of Plex. I could no longer toggle Plex to 'on' in the ReadyNAS gui. I then uninstalled plex and went to the app store to reinstall it. It wasn't there. Does the ReadyNAS 516 still support Plex, I was unable to access the server remotely for quite a few months and took these steps to try to fix it but have made it worse! Please advise.