Jellyfin playback kept freezing on the living room LG TV — the kind of intermittent, hard-to-pin-down issue that immediately points at the server: storage, CPU, the network path, Longhorn (given [the July memory-leak incident](/postmortems/2026-07-31-longhorn-instance-manager-leak) on the same stack). Every server-side signal was checked live and came back clean.
The server was never the problem. Isolated to the TV's own wifi and WebOS buffering behavior — nothing in the server's CPU, storage I/O, or network path correlated with the freezes. Server, storage, network, and CPU were all ruled out with live checks before landing on the TV itself as the actual cause.
No server-side fix, since there was nothing server-side to fix. Added a `NodeRebooted` Prometheus alert rule (bringing the total to 29 rules) as an incidental improvement from the investigation — not a fix for this specific issue, but useful signal for the next time a node-level event needs ruling in or out quickly.
Worth remembering for next time: an intermittent playback issue on one specific client device is not automatically a server issue, especially right after a server-side incident ([July's memory leak](/postmortems/2026-07-31-longhorn-instance-manager-leak)) primes the instinct to look there first. Check the client's own network health early, not last.