I only checked that the received signal was TrueHD (yes from the latest nightly). These are my audio settings. When TrueHD capable receiver + passthrough are enabled there’s no device decoding.
There’s more to network streaming than whether gbit ethernet is present. Play the clip locally from the eMMC or USB stick. Try those caching settings. If the stuttering is present when playing the video from eMMC/USB then enable Kodi debugging and grab the logs.