Outside of Jellyfin, the computers seem to communicate just fine. Transfer speeds are what I would expect and disk read/write is usually fine as well. Like I mentioned in the post, it self-resolved since I made the post. But my concern is the same: what could be causing the underlying issue? I'll check the logs later and I'll report back
Edit: forgot to mention that I have a few 5.1 SACDs @ 24/192k that have always completely choked my system. Doesn't matter which machine or how extreme the transcoded settings are, it nukes the playback