I would double and triple check your not transcoding. Even if you’re watching on the client at whatever the files native resolution is depending on the codec of the file you might still be transcoding. For instance with 1080p anything h265 or AV1 is transcoded into h264 by the server. There’s also a few other situations where Plex with force transcoding or down convert the video whether you want it to or not.
Your NAS shouldn’t be having trouble serving the file to Plex I’d bet it’s transcoding in the background and you just don’t realize it.
I would double and triple check your not transcoding. Even if you’re watching on the client at whatever the files native resolution is depending on the codec of the file you might still be transcoding. For instance with 1080p anything h265 or AV1 is transcoded into h264 by the server. There’s also a few other situations where Plex with force transcoding or down convert the video whether you want it to or not.
Your NAS shouldn’t be having trouble serving the file to Plex I’d bet it’s transcoding in the background and you just don’t realize it.