Hands on with Home Assistant’s new ‘smart home multi-tool’

Nabu Casa, the commercial arm of the Open Home Foundation behind Home Assistant, has released the Home Assistant Connect Aux-2, a $69 accessory roughly the size of a deck of cards. The device packs 2.4GHz Wi-Fi, Bluetooth 5 Low Energy, Ethernet with Power-over-Ethernet support, USB-A and USB-C ports, a 3.5mm digital/analog audio jack, a Grove port for sensors, and two RS-232 serial ports. It is available now and draws power from USB-C or PoE.

The Aux-2 is not a standalone hub; it leans on Home Assistant's existing integrations and runs on ESPHome, the open platform for turning ESP boards into connected devices. Each hardware function maps to software the platform already supports or is developing. The serial integration was completed earlier this year, while Music Assistant and SendSpin — the whole-home audio standard also developed by the Open Home Foundation — remain in active development. SendSpin is intended to group speakers running on different protocols under certain conditions, though that capability is not yet finished.

Setup is handled through the Home Assistant interface. Firmware and Wi-Fi credentials can be loaded from a browser over USB-C before the unit is placed, after which ESPHome discovers the device and walks the user through enabling features. A single unit can drive multiple devices, limited by the number of physical connections: two serial-controlled devices attach directly via the RS-232 ports, and a second Aux-2 can cover equipment elsewhere in the house. The USB-A port accepts Nabu Casa's ZWA-2 Z-Wave adapter, and Bluetooth Low Energy can proxy up to three active device connections. Waveshare's USB-to-RS485 adapter is also supported for RS485 equipment.

The Verge tested the Aux-2 for a couple of days and found it "unsurprisingly useful and surprisingly easy to set up." The reviewer used it to bridge Govee Bluetooth hygrometers in a garage fridge — restoring a monitoring automation that had failed with Zigbee sensors — and to stream music to previously unused in-wall speakers via Music Assistant, a process that took less than half an hour. Serial control for TVs, AV receivers, and solar inverters was not tested due to time constraints. The reviewer noted the Aux-2 does nothing a hobbyist could not assemble with an ESP32 board and accessories; Apollo Automations sells the Cast-1 for $35 with the same music-casting and Bluetooth proxy functions. Nabu Casa and Apollo both fund the Open Home Foundation, and the overlap is by design: both sell hardware that is simpler to deploy than a DIY build, while users remain free to roll their own.

Paulus Schoutsen, founder of Home Assistant and Nabu Casa, said in a statement: "The most sustainable device is the one you already own. No device should be left behind because it doesn't have smart capabilities, or worst of all, its cloud services get turned off." Hackster.io quoted Schoutsen adding: "So bring back that great-sounding, but forgotten, hi-fi and have it play in sync with Sonos or AirPlay speakers. Take that solar inverter or TV with an annoying app and wire it into Home Assistant with a serial connection. Connect AUX-2 helps you take back control of the devices in your home, and because it's fully open, our community will keep finding amazing new uses for it." The launch arrives amid broader debate over planned obsolescence in consumer electronics, positioning the Aux-2 as a low-cost on-ramp to Home Assistant for users who want to revive existing gear rather than replace it.