MacworldRecently, I found that one of our home security cameras that supports Apples HomeKit framework and HomeKit Secure Video for iCloud clip storage had started to flip on and off the local network. I would often see dozens of [name] is offline and [name] is online messages scroll across notifications every day. Sometimes it would remain offline for hours at a time, even though it is within line of sight to a router in the same room and had functioned for months at a time without a problem. Because the camera is inexpensive and a few years old, I purchased a replacement to test whether the original was dyingthe new camera immediately exhibited the same connection issues in the same location.Was the hardware failing? Turns out it was a Wi-Fi connection issue.FoundryThere was a solution. A few months ago, our HomeKit-enabled smart thermostat refused to reconnect to Wi-Fi after a local power outage. I figured out the solution there by configuring a different option on my router. I tested out this solution on both the old and replacement cameras, and it worked. I created a distinct Wi-Fi network to which I connect all smart devices that can be configured to join a specific Wi-Fi network. To explain why and how that works, lets start with a refresher on Wi-Fi.Wi-Fi hits the wallWi-Fi was launched in the late 1990s on the unlicensed 2.4 gigahertz (GHz) band, a range of frequencies divided into narrow, overlapping channels that anyone can use but which isnt guaranteed to be free of other users (unlike cellular frequencies, which are licensed and exclusive to each carrier).This worked well enough for the initial low maximum speed of 11Mbps. As Wi-Fi improved, it expanded into a much larger area of unlicensed spectrum at 5GHz and, more recently, 6GHz. These higher-frequency bands have shorter wavelengths (a function of the number of cycles per second they vibrate at) and have wider channels, which together allow vastly higher data throughput. Modern Wi-Fi in the 5GHz and 6GHz bands can exceed 1Gbps.Those shorter wavelengths, however, have greater trouble passing through walls, ceilings, furniture, and other objects. The longer 2.4GHz wavelengths do a better job of getting through without as much absorption, meaning more signalthus more datareaches a greater distance across rooms and floors. The 2.4GHz band maxes out at about half of 5GHz and 6GHzs top rates, and typically delivers only in the high tens and low hundreds of megabytes per second of data. However, thats enough for smart devices, which often pass very little information. Even a 4K security camera has a datastream that fits comfortably inside 2.4GHzs window.You likely never noticed the performance difference between frequency bands because all modern routers are dual-band 2.4GHz/5GHz or tri-band 2.4GHz/5GHz/6GHz and your devices always strive to pick the fastest data rate, regardless of band. Router makers kept 2.4GHz in their Wi-Fi base stations originally for backward compatibility because possibly hundreds of millions of computers, phones, and other devices had been sold with just 2.4GHz built in (some percentage of those remain in use). But it also helps with range when a router is placed in an area in which 5GHz or 6GHz signals are absorbed a room or more away.HomeKit and other smart devices often include only a low-power Wi-Fi radio, particularly if theyre battery-powered. Many are stuck in the past by only supporting 2.4GHz, too, as that reduces the cost and power consumption.How can you leverage your router and 2.4GHz to improve smart device connections? Set up a separate guest 2.4GHz on a router (or routers) near your smart equipment.Separate networks improve consistencyWhen you set up a Wi-Fi network in your house, you may have a single router or several, or have opted for a mesh network (like that created by where you add nodes that self-configure with other nodes.In most cases, the default configuration has all bands and all routers using the same network name and Wi-Fi password. This allows seamless roaming across your home. However, each of your devices picks which router and band it connects to based on logic built into the device. If your iPhone or security camera selects a weak, distant routers 5GHz broadcast, you cant force it to switch.The way to pick a band and router is to name networks distinctly. Nearly all routers sold in the last decade provide a couple of options for this:You can set a separate name and password for your 2.4GHz and 5GHz (or 5GHz/6GHz) networks.You can enable a guest network in one or more bands with its own name and password, though with some extra configuration needed to work with HomeKit.The first is less useful, as it can affect roaming. Using a guest network makes more sense, as it leaves your main network untouched but gives you the advantage of selection. If you have routers around your house, you may even be able to set up each routers guest networks 2.4GHz radio with a unique name (the password can be identical).For instance, on the router closest to my smart home devices, a NetGear Nighthawk, I have enabled the guest network, set its SSID or network name to broadcast (making it selectable from a menu), and checked Allow guests to see each other and access my local network. That last item is very important: without guests seeing your local network, your smart home devices will be unable to reach your HomeKit hub. The language will vary by router manufacturer and sometimes even among models made by the same company, but there should always be a switch you can set to turn off guest isolation or turn on see devices on the local network.This configuration on a NetGear router locks connected devices to a strong, nearby signal while also letting them interact with the primary network.FoundryOnce I had that network set up, I used the app for cameras, both Eufy models. While they are HomeKit compatible, Eufy also more details configuration and other options within its own app, including updating firmware. Its there that I was able to select the guest 2.4GHz Wi-Fi network and the offline/online toggling immediately stopped.Months earlier, I had used the physical interface on my smart thermostat and a corresponding app to connect to that guest 2.4GHz network. That was more involved: I had to put the thermostat into a special connection mode from its panel, connect to its short-range private Wi-Fi configuration network, and use the thermostats app to select the new 2.4GHz network.Your mileage will varyNot all HomeKit devices can have their Wi-Fi networks changed: some are locked to the network on your iPhone, iPad, or Mac when you add them as an accessory. But those with apps or interfaces may let you pick a Wi-Fi network without disrupting their association with your HomeKit hub and defined home in the Home app.Ask Mac 911Weve compiled a list of the questions we get asked most frequently, along with answers and links to columns: read our super FAQ to see if your question is covered. If not, were always looking for new problems to solve! Email yours to mac911@macworld.com, including screen captures as appropriate and whether you want your full name used. Not every question will be answered; we dont reply to emails, and we cannot provide direct troubleshooting advice.