SMLIGHT
SMLIGHT SLZB-MR2U
- Zigbee
- Thread
Verified September 2026
A dual-radio (CC2652P + EFR32MG21) box, 160x24x28mm, that runs as a Zigbee router/repeater to kill dead spots, or gets reflashed as a Matter-over-Thread border router — useful if your coordinator sits in a cupboard and you need proper mesh coverage at the far end of the house. Power via USB-C or 802.3af PoE, but PoE means a standard injector or PoE switch — it isn't included. This is for people fixing a genuine coverage gap with hardwired placement, not a shortcut to buy a second coordinator instead of solving the mesh properly; pair it with one of the dongles already in this list.
In Home Assistant
| Control | Type | What it does |
|---|---|---|
| Network role | Select (SMLIGHT web UI) | Firmware-level toggle for the Zigbee radio's role — must be set to router for mesh-extender use, not left on its coordinator default. |
| Ethernet link status | Binary sensor | Diagnostic entity reporting wired backhaul state — a downed Ethernet link silently drops the unit out of the mesh with no other HA-visible symptom. |
| Radio firmware versions | Sensor | Two independent version sensors, one per radio chip, reflecting that reflashing the Thread radio doesn't touch the Zigbee radio's separate firmware. |
| Restart | Button | Remote power-cycle — the practical recovery path when a route drops off the mesh, since there are no per-router diagnostic entities in ZHA/Z2M to troubleshoot from directly. |
| Thread border router entry | Diagnostic (Thread panel) | Once reflashed and discovered, it appears here under whichever Thread network it holds credentials for — not as a device or entity, matching how HA treats all Thread border routers. |
As a router, the Zigbee radio never creates its own device or entities in ZHA or Zigbee2MQTT — it's transparent to Home Assistant, surfacing only as a hop in the network topology view rather than anywhere in Settings > Devices. Reflashing to Matter-over-Thread border router mode is an OTA operation on the second radio only, with no cable and no touching the Zigbee side; once flashed, it stops being invisible and instead appears in HA's Thread integration config panel via network discovery, listed as a border router candidate rather than as entities. Because the two radios run concurrently on independent channels, a single unit can act as Zigbee router and Thread border router at the same time — reflashing one radio doesn't cost you the other's job. Its Ethernet/PoE power means it can be hardwired at the actual dead-zone location rather than wherever a USB extension cable happens to reach, which is the real lever for fixing far-end mesh coverage.
Specs
- chips
- TI CC2652P + Silicon Labs EFR32MG21 (dual radio)
- power
- USB-C (5V) or 802.3af PoE (48V, isolated) — PoE requires a standard injector or PoE switch, not included in the box
- roles
- Zigbee router/repeater or Thread border router (reflashable)
- firmware
- Ships on SLZB-OS (Web UI, WireGuard VPN, OTA updates); ESPHome flashing supported, open-source core available
- dimensions
- 160 x 24 x 28mm, 86g, wall-mountable with 3M adhesive strips
- connectivity
- USB-C / Ethernet (RJ45) + USB-A passthrough for dongles