Lost thumbnails on videos with various media servers

[JacktheRipperPhD]

When I use the Windows 10 Media Server for viewing home videos stored on my laptop, streaming to my Samsung TV, the TV displays thumbnails for each file in my laptop Videos Folder. The thumbnails are basically the first frame of the video, as far as I can tell. This makes it very easy to select the correct file to stream.
However, when I try to do the same thing using either uPnP or MiniDLNA for files stored on my Asustor NAS, no thumbnails are displayed on my TV while I'm selecting which files to stream. The videos play just fine, but no thumbnails are displayed, just a filename with a generic icon above it. Does anyone know a solution for this, or is this as good as it gets?