ReadyNAS Server Support - Plex No Longer Working

For a few years I’ve used Plex with my Netgear ReadyNAS. As of a day or two ago, Plex has stopped working - cannot locate servers. My NAS is running. I’ve tried to download the latest, but you no longer have the NAS 4.x download option - only 6.x. I am assuming that I need the latest update - although Plex has never stopped running for me with an older server version. Where are the 4.x Netgear download options? Is my NAS no longer supported or going to work?