Smlight SLZB-MR5U vs Sonoff Dongle Lite MG21

The Smlight SLZB-MR5U is more capable overall, adding Ethernet and PoE placement, stronger +5dBi antennas, dual-network mode and a Bluetooth proxy. The Sonoff Dongle Lite MG21 wins only on price as a simple, budget USB Zigbee coordinator.

Connectivity and features. The Smlight SLZB-MR5U can be placed anywhere via Ethernet, Wi-Fi or PoE and runs Zigbee and Thread simultaneously with a Bluetooth proxy, while the Sonoff Dongle Lite MG21 is a plain USB-only stick with a single antenna and none of those extras.

Yes. Both the Smlight SLZB-MR5U and the Sonoff Dongle Lite MG21 run the Silicon Labs EFR32MG24 and act as a Zigbee 3.0 coordinator and Thread border router. Neither supports Z-Wave, so the difference is in connectivity and extra features rather than the core radio.

The Smlight SLZB-MR5U, with two external antennas rated +5dBi, ahead of the single +3dBi antenna on the Sonoff Dongle Lite MG21. Both use a +20dBm-class amplifier, and the Lite MG21 ships with a USB extension cable to help placement.

Buy the Smlight SLZB-MR5U if you want a flexible, network-connected Zigbee and Thread coordinator you can mount anywhere over Ethernet or PoE, with dual-network mode, a Bluetooth proxy and stronger antennas for a larger Home Assistant setup.

Buy the Sonoff Dongle Lite MG21 if you want the cheapest, simplest way into a Zigbee smart home, a compact USB coordinator (or extra router) that is nearly plug-and-play with Home Assistant and comes with a USB extension cable.