I have an NAS (which is Synology if it matters), and say, if I have a file

Public/Lists/List of Tesla movies.txt

Now if I use Finder on Mac with Monterey macOS 12.5, and go to Public and search using Tesla and “filenames containing”, it cannot find the file, which is obviously there when I open up the folder Lists.

If I use in the Bash or Zsh command prompt (Terminal):

find /Volumes/Public -iname '*tesla*'

then it'd now find the file. However, I may not go through this step using Bash every time, but take the Finder's search result as the answer. The fact that find can find it but Spotlight cannot find it suggests it is not the issue with the NAS. So how can I make Spotlight more reliable and able to find a file by filename?

(I checked the Settings -> Spotlight -> Privacy and that network folder is not part of the “do not index” folder and it never was… and I don't think a pre-built index is used to find files).