A Pro-Grade Smart Home Gateway Powered by an ESP32

A few Wi-Fi-connected light bulbs and a couple of smart plugs controlled by a voice assistant are enough to satisfy most people’s requirements for a functional smart home. Tech enthusiasts, on the other hand, view these entry-level gadgets as merely the tip of the iceberg. They strive for true automation rather than simple remote control, replacing cloud-dependent Wi-Fi devices with local protocols like Zigbee, Z-Wave, or Matter to ensure the house remains “smart” even if the internet goes down.

For these power users, the goal is not to use a voice assistant to turn on a light; it is to design a smart home system that anticipates their needs through a web of occupancy sensors, power monitors, and localized hubs. However, this sort of automation requires more capable hardware than the devices you might find in a big-box store. For starters, a powerful smart home gateway is required.

If you are searching for a new gateway, then the SMLIGHT SLZB-Ultima is worth a look. This ESP32-based device was designed with power users in mind. It comes equipped with radios for just about any wireless protocol that you might want to use, and it can easily be integrated with Home Assistant or even custom smart home controllers.

Built around an ESP32-S3 microcontroller, the SLZB-Ultima provides Wi-Fi 4 and Bluetooth LE connectivity along with enough processing power to manage multiple radios and local automations. What sets the device apart, however, is its dual Zigbee and Thread architecture. It combines a Texas Instruments CC2674P10 and a Silicon Labs EFR32MG24, allowing users to run parallel Zigbee networks, experiment with Thread border routers for Matter devices, or even use one radio as a dedicated router to strengthen mesh reliability.

For those invested in Z-Wave, SMLIGHT offers an optional Z-Wave 800 add-on that works with Home Assistant’s Z-Wave JS over Ethernet or USB. This modular approach continues with support for external USB dongles, enabling additional Zigbee, Thread, or Z-Wave radios without replacing the core hardware. Networking options are equally flexible, with Ethernet support and an optional Power over Ethernet module for clean, single-cable installations.

Wireless radios aside, the SLZB-Ultima includes a built-in infrared receiver and transmitter, allowing it to learn commands from legacy remotes and control older TVs, air conditioners, and AV equipment. There are also GPIO and I²C headers for DIY expansion, a buzzer for audible alerts, three physical buttons, and four service LEDs for local interaction. On the front panel, twelve WS2812B RGB LEDs provide customizable visual feedback for system status and automations.

An optional 4G/LTE module can act as a primary or backup internet connection, making the device suitable for remote or temporary deployments. A microSD card slot and multiple USB ports, including both Type-A and Type-C, support storage and peripheral expansion, while an optional microphone module enables ESPHome-based voice and audio experiments.

On the software side, the SLZB-Ultima runs SLZB-OS, a web-based platform with built-in Zigbee hub functionality, WireGuard VPN support, DDNS, local automations, and over-the-air updates. Users can also flash ESPHome for tight Home Assistant integration, Bluetooth Proxy support, and extensive customization. With pricing starting under $50 for the base model and topping out around $80 for fully loaded configurations, the SLZB-Ultima provides a lot of bang for your buck.