How does one prevent users from accessing the server drive in an explorer after enabling uPnP/DLNA in KODI and EMBY?

password and trusted devices works for me (KODI for raspberry pi) On PC use plex much better user control

…only that Plex requires internet to function properly otherwise on a local network users will still be able to access files in the server.

then get a another router for guests and isolate it from your home network routers are as cheap as 1500 this days