Remote Access No Longer Working - Only changes would be NAS Software and Plex Server updated

That’s due to Plex displaying a „green“ remote access status indicator while it’s attempting to verify if remote access is working. Based on your description, your remote access setup isn’t working, period.

Have you already checked the common troubleshooting steps?

https://support.plex.tv/articles/200931138-troubleshooting-remote-access/