When the smart home compatibility standard Matter finally arrives, it promises to simplify and improve the connections and compatibility between different device brands, using Thread as its secure, low-energy backbone.

Until then, let devices like Wemo's new Smart Dimmer with Thread serve as a warning: Matter runs on Thread, but not all Thread devices will give you a Matter experience. Belkin's new dimmer is a prime example of a device "with Thread" that is far from universally accessible—and likely confusing to buyers.

Wemo's new dimmer doesn't require the onerous Wi-Fi setup you might remember from switches of old, instead connecting to your smartphone by Bluetooth or an NFC tap. To use it outside of Bluetooth range, you'll need a Thread network in your home. But here's where it gets tricky: This smart dimmer is controlled exclusively through HomeKit, so you'll specifically need a HomePod Mini or second-generation Apple TV 4K within a reasonable range of the switch. Those more robust devices can act as "border routers" in a Thread network, allowing more single-purpose devices like a dimmer to connect to a Thread mesh and access the Internet.

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Future versions of Thread will allow more border routers to mesh and handle each other's encrypted traffic—Alexa speakers passing along traffic from Nest cameras, for example. But for now, Wemo's dimmer requires either an entirely Apple-based Thread mesh or controlling it with Bluetooth (which still requires some kind of HomeKit "hub," such as an iPad).

Wemo still offers a smart dimmer switch that can be controlled by Amazon's Alexa, Google's Assistant, and HomeKit. That Wi-Fi-based switch won't work with future Matter systems. But then, neither will Wemo's brand-new, Thread-capable Smart Dimmer: The company told The Verge that it "will bring to market new switches/dimmers that support Matter over Thread" later this year.

(Update: Cassie Pineda of Belkin tells Ars, regarding the Smart Dimmer with Thread's limited connectivity: "We launched a HomeKit-exclusive Smart Dimmer with Thread to provide our customers with a more responsive, reliable and secure smart home experience without the hassle of third-party apps. This product is a stepping stone for our customers that want the latest technology with Thread as we wait for Matter.")

Before Matter's official (hopeful) rollout later this year, it might be good to hold off on new smart home purchases to see if and how they'll work with the new standard. At the same time, don't assume that something that seems Matter-ready will be. There's still a lot left to unravel in the Thread space.

Listing image by Wemo