That’s why I’m sticking to Zigbee as much as possible. The only place where there’s an internet connection is at the Home Assistant computer which has a Zigbee USB stick.
I settled on Zigbee for door, window and some motion sensors, stand-alone buttons and other devices that need to be battery powered but for everything that's built into a wall or perma-attached to an outlet (like light switches, dimmers and wall plugs) I use generic commodity hardware running open source Tasmota firmware. These devices are based on standard reference designs, made by multiple Shenzen manufacturers and dirt cheap via Amazon, eBay and AliExpress. They're mostly based on ESP-8266 or ESP-32 chips and communicate via wifi.
The reason I use wall-powered wifi devices alongside Zigbee is the Zigbee architecture was designed to enable tiny battery powered devices that can run for a year or more on a small battery. Zigbee does this really well but I didn't want to be changing batteries on nearly a hundred wall switches, plugs and sensors that are connected to 110V anyway or perma-installed in places where wall power was easy to supply. There are also many devices like ultra wide band motion sensors, RF bridge repeaters, etc that can't be battery powered for long periods.
This Wifi+Zigbee split architecture has worked flawlessly in both our primary residence and a vacation home but they are both large detached homes, well-covered by wifi mesh routers with wired backhaul and other 2.4Ghz wireless neighbors a hundred or more feet away from our outer walls. So it's important to test wireless range and environmental compatibility inside your specific wall construction and unique RF domain before settling on wireless standards and architecture and installing a bunch of devices. Also, I'll mention that it's always tempting to just use wireless backhaul because it's easy but I think a big reason my large, complex home automation installs have avoided issues with randomly varying latency and intermittent signal loss is that I put in extra effort to get gigabit wired backhaul to each wifi mesh node and wired a Zigbee node alongside each wifi node. This entailed getting creative, like using an old pre-existing coax cable run with a Docsis modem to one mesh node and powerline ethernet to another. I'm pretty sure that extra pain up front prevented a lot of niggling gremlin pain later.
Zigbee has hardwired switch options so you aren’t replacing batteries, but I haven’t done a lot of them because they’re far from dirt cheap. Only in places where I find automations or smartphone control to be particularly useful, or where existing dimmers died and I figured I might as well upgrade.
Inovelli Blue are the ones I’m using, but at $50 each they’re competing against products like Lutron Caseta.
In some other places where it’s not just wanting the zigbee control, but also that the hardwired switch is in a stupid location, I’m using IKEA’s RODRET remote combined with their relatively cheap Zigbee bulbs, instead of Zigbee wall switches. They run on AAA batteries and seem to last quite a while, but I can’t say how long yet.
For plug-in lights where you just want on/off (garage strip lights for instance) their TRETAKT Zigbee outlet is a steal at $7. There’s a fancier version with energy monitoring too.
I sleep a little better knowing all my line voltage devices are from real brands with UL or equivalent testing, and the only cheap parts from mystery vendors with unknown certifications are 3V coin cell door sensors.
Actually, the non-battery-powered devices are the important part of Zigbee network. In Zigbee network, only coordinator and router can * route* the tracfic, others device can only send or receive. So if there is no other router or only few router, the Zigbed network will degrade from mesh topology to star topology. Because of power limit, the battery-powered devices are not suitable for router role so they almost is an end device. The AC-powered devices normally do router role.
This is why I haven't fully bought into Zigbee for any device that could possibly be wired and Wifi. I've already invested considerable money building a 2.4G (5G, really) wireless network: why not throw a few more relatively quiet devices on there. Zigbee is on the overcrowded 2.4GHz spectrum anyway.
Slightly off topic but I just bought an inexpensive water leak monitor set and it uses LoRa — I’ve had range problems with other bands “Extremely Long Range: Powered by LoRa technology, the long-range low-power system offers the industry’s longest receiving range (1/4 mile). Areas such as basements and sheds connect up to 100 sensors to deliver product information smoothly.”
LoRa sounds like a good idea for water sensing in particular. Water catches all radio signals at 2.4 GHz and turns the waves into heat (that's why microwave ovens work, after all), so spread-spectrum transmission seems like a good way around that issue. I would test the transmission range in a bathtub.
