Both smartdomo starter kits pair the same brain, a Home Assistant Green, with a different radio for Zigbee, Thread and Matter. Home Assistant handles Wi-Fi and Ethernet devices on its own, but Zigbee and Thread need a dedicated 802.15.4 radio plugged in. That radio is the "antenna" being compared here, and it is the only thing that differs between the two boxes. See Home Assistant for the platform itself.
The useful news: both radios run the same Silicon Labs EFR32MG24 chip, so raw Zigbee and Thread capability is identical. The choice is about the antenna and how the radio connects to the hub, not about the silicon.
Bottom line
- Home Assistant Connect ZBT-2: the official first-party radio. One external antenna, plugs into the Green over USB-C, simplest possible setup, best-supported. Pick this if you want it to just work.
- Sonoff Dongle Max: two higher-gain antennas and, more importantly, it runs over Ethernet with PoE or Wi-Fi, so you can mount it anywhere instead of next to the hub. More capable, more knobs, younger firmware. Pick this if coverage or placement is the problem you are solving.
The two kits
The ZBT-2 kit. Green plus the official Nabu Casa radio.
The Sonoff Dongle Max kit. Green plus Sonoff's networked multiprotocol coordinator. Cheaper by €15.
Head to head
| Spec | Connect ZBT-2 | Sonoff Dongle Max (ZBDongle-M) |
|---|---|---|
| Radio chip | Silicon Labs EFR32MG24 | Silicon Labs EFR32MG24 (+ ESP32 for networking) |
| Antennas | 1 external, 4.16 dBi | 2 external, 5 dBi |
| Connection to hub | USB-C only (1.5 m cable) | USB-C, Ethernet + PoE, or Wi-Fi |
| Protocols | Zigbee 3.0, Thread, Matter-over-Thread | Zigbee 3.0, Thread, Matter-over-Thread |
| Zigbee + Thread at once | No, one protocol at a time | No, MultiPAN is beta only |
| Software | ZHA, Zigbee2MQTT, OpenThread Border Router | ZHA, Zigbee2MQTT, OpenThread Border Router |
| Housing | Plastic, upright stand | Aluminium |
| Extras | First-party, simplest setup | Web console, PoE, AP hotspot, WireGuard |
| Standalone price | 49 USD / ~45 EUR | ~30 EUR |
| Kit price (smartdomo) | 224,90 EUR | 209,90 EUR |
The antenna question
On paper the Sonoff wins the antenna spec: two 5 dBi antennas against the ZBT-2's single 4.16 dBi. In practice that gap is small. A dedicated external antenna already fixes the thing that actually kills Zigbee range, and both have one. Doubling up and adding under 1 dBi of gain is a minor improvement, not a different league.
The bigger antenna story is placement, not gain. Zigbee at 2.4 GHz hates two things: distance to the nearest device, and RF noise from the hub itself. USB 3.0 ports, SSDs and the metal of a NAS shelf all splatter noise across 2.4 GHz. The ZBT-2 ships with a 1.5 m USB-C cable precisely so you can lift the radio off the hub and away from that noise. Good, but you are still tethered to a cable near the Green.
The Sonoff Max breaks the tether. Because it also talks Ethernet with PoE, you can run it on a single network cable and mount it in the centre of the house, upstairs, wherever coverage is worst, drawing power from a PoE switch. For anyone with a PoE network already (I run UniFi), that is the real advantage: put the coordinator where the mesh needs it, not where the server happens to sit. Two extra antennas are a footnote next to that.
What is actually the same
- The radio. Both are EFR32MG24. Same Zigbee 3.0 stack (EmberZNet / EZSP), same Thread support, same Matter-over-Thread story.
- The software. Both work with ZHA and Zigbee2MQTT for Zigbee, and both can run an OpenThread Border Router for Thread and Matter.
- The one-radio limit. A single MG24 does Zigbee or Thread, not both at once. Running both concurrently (MultiPAN) is experimental on the ZBT-2 and still beta on the Sonoff. If you want a solid Zigbee network and a solid Thread network, buy two radios, one dedicated to each. This is the standard advice and it applies to both kits.
Real-world caveats
- Sonoff Max is new (late 2025) and it shows. Home Assistant forum and Reddit reports at launch include devices dropping off, laggy networks, and broken light groups, plus flaky Thread-over-Ethernet (reviewers suggest running Thread over USB instead). The hardware is good; the firmware is maturing. Worth checking current state before committing a large Zigbee network to it.
- ZBT-2 is the safe default. First-party, tightest Home Assistant integration, and the one the docs and community assume you are using. Less to go wrong. The trade is the single antenna and USB-only mounting.
- PoE freedom has a footnote. The Sonoff's network mode is where the firmware is least mature. If you buy it for PoE placement, that is exactly the mode carrying the most launch bugs. Verify it is stable now, or run it over USB and lose the main reason to prefer it.
Which one for me
For a first Zigbee network with the least fuss, the ZBT-2 is the right call: official, simple, well supported, and the single external antenna is enough for a normal flat. The €15 saving on the Sonoff kit is not worth younger firmware on your first build.
The Sonoff Dongle Max earns its place the day coverage becomes the problem, a far corner or a second floor the mesh cannot reach cleanly, because PoE lets me mount the coordinator dead centre off a UniFi switch. I would reach for it as a deliberate coverage fix once the network is mature, not as the starting radio.
Further reading
