Thread vs Wi-Fi: which to buy for each device

Matter runs over two radios in the home: Thread and Wi-Fi. A Matter product is built for one of them at the factory, so you answer this question one purchase at a time rather than once for the whole house.

If the thing plugs into the wall, the transport barely matters. If it runs on batteries, it decides whether you are changing cells every few months or every couple of years.

What actually differs

Thread is a low-power mesh built on the IEEE 802.15.4 radio, the same radio Zigbee uses, running at 2.4 GHz and about 250 kbps. That is plenty for "the back door opened" and nowhere near enough for video. Mains-powered Thread devices relay for their neighbours, so a Thread plug in the hallway quietly extends coverage to the sensor at the back of the house. Battery devices do not relay. They sleep with the radio off and wake to check in with one parent, which is the whole reason they last.

Wi-Fi is a star. Every device talks straight to the router at speeds that carry a 4K stream, and nothing relays for anything else. A sensor in the back shed is either in range or offline.

Both carry Matter as ordinary IP traffic. Once a device is commissioned, Matter behaves the same either way: same app, same local control, same automations.

Battery life is most of the argument

A Wi-Fi client holds an association with the router and re-associates whenever it drops, which costs power all day. A Thread sleepy end device shuts its radio off between check-ins, and its parent holds any messages until it wakes.

That gap is what you see on the packaging. Aqara rates its Motion and Light Sensor P2, a Matter over Thread sensor, at up to two years on two CR2450 cells. Not every Thread sensor gets there, and reporting frequency does more damage than the radio does: a hallway motion sensor will never match a contact sensor on a spare room window. Wi-Fi sensors claiming long battery life get there a different way. They run Bluetooth or Zigbee to a mains-powered hub, and the hub is the thing on Wi-Fi.

Thread needs a border router, and you may already own one

A Thread border router joins the Thread mesh to the rest of your network. Without one, Thread devices can still talk to each other, but nothing outside the mesh can reach them, so there is no app control, no voice control and no automations.

You probably do not need to buy one. The common ones in Australian homes:

• Apple TV 4K, HomePod mini and HomePod (2nd generation). On the 3rd generation Apple TV 4K, only the Wi-Fi + Ethernet model has the Thread radio.
• Google Nest Hub (2nd gen), Nest Hub Max, Nest Wifi Pro and the Google TV Streamer.
• Several Amazon Echo and eero models, and Aqara's M-series hubs.
• Home Assistant Yellow, Connect ZBT-1 or Connect ZBT-2, once you swap them off their default Zigbee firmware and run the OpenThread Border Router app.

Extra border routers add coverage and remove the single point of failure, and they need not be the same brand.

What happens when something drops out

If the border router loses power, the Thread mesh keeps talking to itself but you lose all control of it until the border router is back. Where your only border router is also your hub, the automations stop with it.

Wi-Fi splits differently. If the internet drops but the router stays up, commissioned Matter over Wi-Fi devices keep working locally, because Matter control is local by design. Remote access and cloud voice go, the devices do not. If the router itself reboots, every Wi-Fi device drops off and has to reconnect.

So neither transport is the reliable one. Thread starts with more single points of failure and ends with fewer once you add a second border router. Wi-Fi has exactly one, and you already depend on it for everything else.

One Thread gotcha worth knowing: Home Assistant cannot push Matter firmware updates through a Thread network made up of Apple border routers, because Apple's implementation does not forward the packets needed to find the update provider. Normal control still works, but updates need another border router in the mesh.

They both live in the same 2.4 GHz band

Thread does not get you off 2.4 GHz. It shares the band with Wi-Fi, Zigbee and Bluetooth, and there are only three non-overlapping 20 MHz Wi-Fi channels to fit all of that into. What Thread does is move the chatter onto a separate low-rate network, instead of adding dozens more clients competing for airtime with laptops and televisions.

Client counts matter too. TP-Link rates the Deco M4 for 100 connected devices and Google rates Nest Wifi Pro at 100 per point. Those are ceilings rather than comfortable operating points, and 30 Wi-Fi bulbs, plugs and sensors is a real slice of the budget.

One Wi-Fi annoyance to know before you buy: Matter Wi-Fi devices are almost always 2.4 GHz only, and commissioning fails if your phone has been steered onto 5 GHz on a combined network name. Turning 5 GHz off for a minute fixes it, as does keeping a separate 2.4 GHz network.

You will run both, so buy for the device

Some categories decide for you. Cameras, video doorbells and robot vacuums are Wi-Fi because Thread cannot carry what they send. Battery sensors, locks, blinds and thermostats are where Thread earns its keep. Bulbs, plugs and switches come both ways, and being mains-powered the transport matters little, though a Thread one strengthens the mesh.

Most Matter products on sale today are Wi-Fi, because manufacturers ship what works with no extra hardware in the house.

Our position: if you already have a border router, prefer Thread for anything running on batteries and stop thinking about it for everything else. If you do not have one yet, buy Wi-Fi now and add a border router with your first battery sensor. What is not worth doing is passing on a product you actually want because of the logo on the box.