audioOS 9.9.18.3 (build 22K557) is an official Apple over-the-air update for the HomePod (2nd generation), released on 2025-01-27T18:19:49Z. The update package is 1.5 GB. This is a delta (partial) update that requires 16.3 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 4703bcacf0c466a82d676931ffc44c506e6e72d16cc3cc8059740b5c6176bd9c.aea.