I posted this on another thread, and for the record, I am 100% newb to all things NAS. I have now also set up the Jellyfin app on my roku box and can stream media perfectly across my home network:
I managed to install Jellyfin today, it was pretty easy (on the third attempt!!)
Before install I created a media folder as a public folder in HexOS, then created subfolders therein for movies, music, etc. Then installed in TrueNAS, left everything as default except for additional storage which was setup as:
Type: Host path (Path that already exists on the system)
Mount path: /media/movies (or other type)
Host path: navigate to, or type path to folders you created before install (for me was: /mnt/HDDs/Media/Movies etc)
Complete install, then in Jellyfin UI go through the wizard, and when you get to media libraries, select type, and display name, click +Folder, and browse from the drop down to the corresponding Host Path.
I can access it fine from a browser on my phone, haven't got to the point of using the Jellyfin client on other devices yet.
The reason I hadn't set myself up a NAS before now was that I was genuinely intimidated at the process, but the LTT video and HexOS showed me just how easy it can be. Not saying the above will work for everyone, but I tried a few times before getting Jellyfin to work.