audioOS 9.9.18.4 (build 22L255) is an official Apple over-the-air update for the HomePod (2nd generation), released on 2025-03-31T17:29:49Z. The update package is 1.22 GB. This is a delta (partial) update that requires 17.5 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: d8a6b3cdce678ae8b0bb3e54bce7a579369a06c23827a624eb16f963e476e989.aea.