The Connect ZBT-2 is Nabu Casa's second-generation USB radio for Home Assistant, replacing the ZBT-1 (formerly SkyConnect). It's built around a Silicon Labs MG24 for the Zigbee/Thread radio paired with an ESP32-S3 handling the USB-serial bridge, running at 460800 baud — four times the ZBT-1's rate. The practical effect is noticeably faster device responsiveness, since the adapter itself is no longer the bottleneck between the network and Home Assistant.
It ships for $49/€45 with an external antenna and base, a departure from the ZBT-1's internal antenna. The case opens without clips or glue, with exposed pins and pads for anyone inclined to tinker with it.
Single protocol, not both
The ZBT-2 can't run Zigbee and Thread simultaneously. Nabu Casa tested multiprotocol operation on the ZBT-1, found it unreliable, and dropped the idea for this generation entirely — each ZBT-2 is dedicated to one protocol. For a network that's fully moved to Matter over Thread, this isn't really a constraint in practice, since the device's whole job becomes acting as a Thread border router without a legacy Zigbee mesh sharing the radio. It only becomes a limitation for networks still running both protocols side by side, which would need two adapters rather than one.
Limitations
The ZBT-2 can't act as a Zigbee repeater. It also can't run as a standalone Thread border router independent of Home Assistant — the Thread network only persists while Home Assistant is running. There's no Power-over-Ethernet option, so it's USB-C only, and Nabu Casa's own documentation recommends an extension cable to keep the antenna out of a router's RF shadow. These are unremarkable limitations for a $49 adapter, but they set a ceiling on what the device is for: one Home Assistant instance, one antenna, nothing more distributed than that.
Migration path
Nabu Casa publishes migration wizards for both Zigbee and Thread adapters that cover most existing hardware, with a few exceptions — Conbee sticks need a firmware change first. The relevant path for a Thread-only setup is their guide for dedicating a Connect device to Thread, which is how the ZBT-2 gets set up as a Matter/Thread border router rather than a Zigbee coordinator.
Summary
As a dedicated Thread border router, the ZBT-2 brings a better antenna, a faster baud rate, and first-party support that tends to get Matter and Thread updates early. The single-protocol design, a drawback for mixed Zigbee/Thread households, is simply irrelevant once a network has fully moved to Thread. The remaining limitations — no standalone border router mode, no repeater support, USB-C only — are the same ones any Thread setup runs into regardless of which adapter is used.