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In recent years, I've received many questions about issues with Wi-Fi connections involving smart Wi-Fi devices. The increasingly widespread use of IoT (Internet of Things) gadgets that hook directly to your Wi-Fi network has its consequences.
Despite the "smart" notion in the name, it can be a bit, well, "dumb" to use these devices willy-nillyโthey may cause all sorts of connection issues for traditional Wi-Fi devices, such as computers or smartphones. It's all in how Wi-Fi broadcasters handle their signals, as described in a setting called "Airtime Fairness".
I'll explain, in simple terms, Airtime Fairness, why it's never a good idea to use many "Smart" Wi-Fi devices in your primary network and what you can/should do to best handle them.
Note: We're talking about standard Wi-Fi devices and not IoT devices with any other type of wireless connection, such as Zigbee, Z-Wave, Thread, or the low-power Wi-Fi HaLow.
Airtime Fairness: How it’s not the best way to deal with IoT smart Wi-Fi devices
Internet of Things (IoT) is a different name for a smart Wi-Fi device.
Once upon a time in the tech world, these devices either didn't exist or lacked wireless connection capability. In recent years, their latest generations have emerged with built-in Wi-Fi, enabling them to connect to the Internet and exchange data with other devices. They can do much more than their older cousins or ancestors, which is where the "smart" notion comes from.
Everyday Wi-Fi-enabled gadgets in the home are examples of these IoT devices, including security cameras, printers, door locks, doorbells, power switches, lights, ovens, refrigerators, grills, and more. Nowadays, it's hard to find any type of home appliances that don't have Wi-Fi-enabled options.
At the gist of it, IoT smart devices are Wi-Fi clientsโthey are network devicesโwith limited functionality compared to traditional clients, such as computers or smartphones. They join the growing list of Wi-Fi devices that has created the need for a particular setting in Wi-Fi broadcasters (access points or routers) called Airtime Fairness.
So, what's Airtime Fairness?
It's a familiar network setting dating back to Wi-Fi 4 (probably earlier) that ensures each client in the network has equal airtime with the broadcaster, regardless of their operating system, Wi-Fi standard, operating mode, or signal strength.
IoT or not, all devices connected to a Wi-Fi broadcaster will need some time to finish transmitting data. That duration is called the "airtime".
Still, it's hard to define airtime since Wi-Fi is a dynamic environment, not to mention other related features, including MI-MO, MU-MIMO, and ODFMA. So, everything you're about to read has been simplified to show an idea of how things work or, well, don't work.
Airtime Fairness turned off: First come, first served
When Airtime Fairness is turned offโthe default case of most modern broadcastersโthis is generally the norm:
The relationship between the Wi-Fi receivers (clients) and a broadcaster is on a first-come-first-served basis.
A broadcaster can handle multiple clients at a timeโup to a certain number. During this time, it generally takes the slowest client's connection rate as the effective rate of all connected clients on the same band (5GHz or 2.4GHz).
When a broadcaster reaches the maximum number of simultaneous active clients it can handle, a newly active client must wait for its turn. Hundreds of clients can stay connected to a broadcaster, but only so many can be active simultaneously.
This wait time depends on how slow the currently active ones are and how much data they need to transmit. But inefficiency is inevitable even when you have just one slow device involvedโit determines the connected speeds for the rest of the pool within the same band. That's because the broadcaster will not do anything about a new (possibly much faster) client until it's done with one of those it has at hand.
Again, that's first-come-first-served.
A crude analogy of first-come-first-served: You might have experienced long checkout lines in a big store. Everybody might have same-size shopping carts, but some are full of small items while others are half-full or even close to empty. If you have just one or two items in your cart, behind a person with a full cart, you'll have to wait for a long time before your turn.
Airtime Fairness turned on: Equal airtime
With Airtime Fairness turned on, the access point now allows a dynamically determined equal amount of time to each client, regardless of performance grade or the amount of data they need to transmit.
For example, if the equal amount of time is determined at 5 seconds, a slow client that needs 20 seconds to finish transmitting its data will have to pause after 5 seconds and wait for the access point to deal with one or more clients, each for 5 seconds. And then it'll get back to its turn. So on and so forth.
That said, with Airtime Fairness turned on, fast clients get benefits at the expense of slower ones. How efficient this pans out depends on the situation: how many slow or fast devices are involved, how significant the performance gaps between them are, and how much data each needs to transmit. It's complicated and super unpredictable.
But as a whole, in terms of the total data being moved, this method is better than first-come-first-served when there are one or a few fast clients involved.
The retail store analogy: Airtime Fairness is like when the cash register spends no more than one minute on each customer. As a result, those with a full shopping cart, who might need five minutes to be processed, will have to wait for five turns to be fully processed, during which a few of those with one or two items can get out first. But carts that need only slightly more than one to two minutes to process will also need to do multiple turns. It gets touchy and complicated.
Airtime Fairness: Why it’s not ideal to handle lots of IoT smart devices
As you can imagine, Airtime Fairness is a "cheat" way for an environment with mixed clients. It's more applicable to public Wi-Fi or in situations where you can't avoid slow, legacy clients.
That includes modern IoT clients using low-power protocols, such as Constrained Application Protocol, a.k.a CoAP.
While it might improve things in certain situations, it's not ideal and can cause unexpected issues, such as the slow real-world connection rates of low-end devices. This becomes severely problematic when you have more than a few IoT smart devices on the same frequency band. Things can get slowed down to a crawl.
Additionally, Airtime Fairness requires extra processing power from the broadcaster, which can cause the high-end clients connected to a different band to underperform or the broadcaster itself to crash after a while.
For this reason, if you choose to turn on Airtime Fairness, it's a good idea to restart your routerโor schedule it to do soโevery couple of days.
Three ways to best handle IoT smart devices
The point here is that in a home where you have complete control over the hardware, it's best to avoid having slow and fast clients mixed in the same Wi-Fi network. Again, most IoT smart Wi-Fi devices are slow clients.
That said, here are a few ways to effectively use smart devices without using Airtime Fairness.
1. Cut down the number
The best way to have a well-performing network is to remove all slow, dated, legacy devices.
A single slow client may cause the broadcaster to lower the Wi-Fi bandwidth of a particular bandโit has to support the lowest denominatorโreducing the connection speeds of all connected clients.
Keep in mind that, unlike traditional clientsโphones, laptops, etc.โwhich are active periodically, smart IoT devices tend to be working all the time, permanently hindering the broadcaster. Three reasons:
- They are designed that way. For example, an IP camera uploads footage constantly to a server.
- They are slow and need more time to finish transmitting a small amount of data.
- They are designed to do more than the advertised functions.
Generally, it's best not to use these devices or have more than a handful in your homeโI'd say no more than five in a home network.
Cloud-recording cameras and your broadband
There's a prevalent Wi-Fi bandwidth assumption that's the root of so many connection problems.
Folks tend to assume that if a Wi-Fi router works well with one particular device, it will work equally well with many. Specifically, if they successfully connect one unit to their Wi-Fi router, they'd go ahead and get ten, assuming they all will work the same.
Just because you can successfully foster one or two small children doesn't mean you can take care of five simultaneously.
The most popular example is cloud-recording IP camerasโArlo, Nest, Ring, etc.โwhich, in addition to negatively affecting local Wi-Fi, also put a massive strain on the WAN upload pipe. A few of these in a network with a modest broadband connection, especially Cable Internet, can render the entire system unreliable, causing other devices to be disconnected sporadically.
Again, if you have a modern (Wi-Fi 5 Wave 2 and newer) network, clients of older standards (Wi-Fi 4 or earlier) slow everything down. To put things in perspective, there are reasons why freeways are closed off to cyclists and pedestriansโeven one of them can cause a traffic jam.
However, removing all low-quality or slow devices from a network can be cost-prohibitive. The next best thing is to create a separate network for them.
2. Segmenting your network
Generally, it helps to put similarly slow devices in a group so that they will not affect the performance of higher-performing parties. You can do so by making different Wi-Fi networks (a.k.a SSIDs) for them.
If you have a dual-band router, name the 5GHz and 2.4GHz bands as two separate SSIDs and use the latter for slow devicesโTri-band or Quad-band broadcasters give you even more options for network segmenting.
Some routers (or mesh systems) don't allow you to separate theirbands. In this case, you can create a Guest Wi-Fi, preferably with intranet accessโthis network almost always uses the 2.4GHz band. Additionally, if the broadcaster has an option of creating a separate IoT Wi-Fi network, use it for your IoT smart devices.
No matter the situation, you can always get a separate access point (or Wi-Fi router)โpreferably of an older standardโand use it specifically for low-end, dated Wi-Fi IoT devices.
Tip
When upgrading your network by replacing the router, you can keep the old router and use it in the AP mode as a separate network to host existing (and new) IoT devices.
Using a separate AP can cause unnecessary interferences when not set up correctlyโyou need to put its SSID in different channels from those of the primary network. But dealing with Wi-Fi is always about nuance.
Real-world example: Segmenting your home network is similar to having "express" checkout lanes for customers with a few items, leaving the regular lanes for those with a full cart. You can find this practice at many grocery stores.
3. Opt for non-Wi-Fi IoT smart devices
Due to the low bandwidth, many high-quality IoT devices tend to use a separate wireless standardโsuch as Thread, Z-Wave, or Zigbeeโfor their connectivity.
Specifically, they use one of these wireless standards to connect to a central deviceโoften called a Smart Home hub. Each hub can handle multiple IoT devices, and it is the only device that connects directly to the home network via Wi-Fi or a network cable, reducing or eliminating the negative impact.
Another example is the Arlo Wi-Fi security cameras, which use a proprietary Wi-Fi link to connect to a hub, which connects to the network via a network cable.
In other words, modern IoT devices are designed not to interact directly with a Wi-Fi network. You can use these instead of those with built-in Wi-Fi.
As mentioned at the beginning, there's a new Wi-Fi standard for low-bandwidth devices called Wi-Fi HaLow. When widely adopted, it'll be an appropriate wireless standard for IoT. We'll still have to wait to see how that pans out.
The takeaway
Here's a general idea: Not all IoT Wi-Fi devices are bad, but none are good for the networkโat best, they are OK. Cheap, no-brand-name ones are almost always terrible.
Generally, if you buy a new device today and it supports Wi-Fi 4 (802.11n) or older (802.11g/a/b) or only the 2.4GHz band, that's a telltale sign it isn't good. But if you get one that supports the 5GHz, it's not necessarily good, either. Chances are it'll still slow the entire band down to a degree.
Just because a device supports Wi-Fi doesn't mean it supports the latest standard or uses up-to-date specifications. That's similar to the fact that while you can physically ride a bicycle or take a walk on a freeway, there are plenty of reasons you shouldn't do so.
As you upgrade the broadcaster side of your Wi-Fi network, it's always a good idea to use clients of the same or similar hardware specifications. If keeping slow clients is a must, use a separate SSID or, better yet, a different broadcaster for them.
To put it in somewhat of a pun, just because a device has "smart" in the name doesn't necessarily mean it's always a smart decision to use it. You can make them work, but things will get complicated, and you might end up inadvertently hindering your top-notch router or mesh system and everything else in your home network.
Dong's note: I first published this post on January 8, 2022, and last updated it on January 25, 2024, to add the latest relevant information.
For anyone following this advice, be aware that the iOS Home app may cease to function as expected. The app uses the iPhone’s SSID which would likely be the 5GHz band, while the IoT devices would be on a different SSID (many of mine are 2.4GHz-only). The devices need to be able to “see” each other.
Unless Apple reworks Home.app to merge devices from multiple SSIDs, the IoT devices that you actively interact with (e.g., smartplug for turning on/off light) would likely need to stay on a dual band SSID. Don’t expect to use Siri as a workaround either.
Not advocating for either SSID naming approach; just don’t spend the night migrating everything to a new broken-out SSID w/o realizing these ramifications. It’s a trade off for performance/security against ease-of-use.
Per the stuff you wrote, the advice is exactly what they should follow, Paul. Make sure you READ before leaving a comment.
I gave a specific example, one that bit me (hard) when I experimented with brand new TP-Link Matter smartplugs — of Apple’s home automation software not working as expected, though the IoT devices themselves had been functioning as expected prior to being SSID segregated.
I called myself having read this article but saw nothing relevant that discussed this, even upon reread. My apologies if I offended.
It’s relevant in the sense that folks shouldn’t count on “smart” in these smart devices, Paul. But this post on isolation may explain your situation a bit more.
No offence was taken.
“…โsmartโ IoT devices tend to be working all the time. …Generally, you should not use them at all,…”
Seriously? Pretty sure that’s what the local smith and livery owners were people about cars a century ago, too. Smart Home devices are here now, however new and limited they are. And they aren’t going away. The better prepared people are, the less negative impact these things will have on their lives. Telling people not to use them isn’t going to prepare anyone for anything.
Read the whole post, Chris. Seriously, that’s a *wise* thing to do before you make a statement like the one you just did.
It’s interesting you suggest scheduling restart every couple of days if Airtime Fairness is enabled. My 2-router AiMesh system would just stop working every 2-3 days and require me to restart both devices. I’m hoping disabling ATF fixes this.
I’ve also gone ahead and disabled MU-MIMO, OFDMA, and Beamforming. Will enable these one-by-one to find the culprit behind buggy AiMesh.
“If you have a dual-band router, name the 5GHz band and 2.4GHz band differently.”
^^ This! For everyone reading this article, THIS is one of the keys to good WiFi performance and it cannot be understated. One too many times you have your WiFi 5/6 devices roam to 2.4Ghz and stay there forever until they reconnect (or roam to a different mesh node), resulting in horrible performance, usually due to the 2.4Ghz band being over-congested with neighbor APs, let’s not even begin to consider IoT devices that will exacerbate the mess…
IF your WiFi mesh/router allows it, separate bands on different SSIDs. If it doesn’t allow different SSIDs per band, upgrade to
something that will (Asus/Linksys come to mind). You’ll thank Dong later for this advice.
Hi, just discovered your site. Very interesting! Is 80 connected devices too much for any router? I think 60 are cheap “smart” devices. My Asus AC87U is loosing 2.4 and 5G randomly, more often lately. Would the AX86U handle it better?
No router can handle those many cheap smart devices, Dott. Give the post a serious read and you’ll know what you can and should do.
Hi Dong, I spent the whole evening migrating all IOT’s to my guest networks (2 routers). Let’s see..
That will likely cause the band to run out of bandwidth fast. But hope it works.
What an interesting read. Like many I’m beyond the point of no return, I’ve got a large number of smart plugs and bulbs all on the 2.4 network so need to find a way to make them work without impacting the network for real users.
I’ve got an Aimesh over 5 routers, using ethernet backhaul, covering the house and garden,
so I’m thinking the simplest solution is to activate one or more guest 2.4 networks and move the smart devices over to those?
At the moment I’ve got channel select set to auto but again I think you are saying it’s better to fix the channel for each network and keep them separate?
Ideally I’d love to create a smart router and push all the smart devices into it but given the fact that they all wouldn’t “reach” a single router I guess that’s not an option?
are there any tools you recommend to see what smart plugs are doing to the network, I stupidly thought they just say there doing nothing unless asked to do something!
I’m a bit new to this but want to learn…. I’m very much at the level of your Costco queue analogies
Hello Dong, 3 quick questionsโฆ.
I have Ring doorbell, 5 Ring security cameras, 2 Ring Motion lights that connect to the Ring bridge and 1 Ring Chime.
When installing these I understood they work exclusively with the 2.4 GHz band.
All TVโs, computers, phones, tablets inside the house connects to the 5Ghz band.
1) Can I assume I have โnaturalโ band selection although I run one single SSID on my Orbi RBR50 with 1 satellite?
Will be upgrading to Asus GT-AXE16000 with one wired ET12 as soon as the AXE becomes available (or maybe two wired ET12 if I get tired of waiting).
2) Is it safe to assume that the โnaturalโ selection will remain with the Asus mesh?
Currently using ADT wired alarm with 29 window/doors contacts, 3 motion sensors, 10 smoke sensors, 2 heat rise sensors & 2 sirens/speakers. Planning to migrate all to Ring alarm.
3) Will this be too much for either of the two Asus mesh mentioned above? Keeping all other Ring items mentioned above.
Best,
Luis
I’m not sure what you meant by “natural”, Luis. But *read* the post, you’ll find the answers.
So Iโve been suspecting this for a while. Iโm thinking about using my TP-Link AX4400 as an access point with a separate SSID and connect it to my ASUS AX89x. Let the smart plugs, printer, and webcam fight it out on the โkids tableโ AP and the adults will sit at the ASUS table. Thoughts? Besides the fact this is overkill. (My tplink gear has yet to sell on Facebook marketplace)
That works, Tyler. Better yet, manually make the TP-Link use separate channels on the same bands as those of the Asus.
1, 6, 11. Kid stuff.
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Hello and thanks for this information/advice. Sadly, I already have a fair investment in IoT/Smarthome devices that employ wifi (all on the 2.4Ghz band) so just getting rid of them is not a likely solution. I do have a few more modern phones that connect via 5Ghz and 3 ethernet devices (TV, Chromecast, and an Android computer used mostly for Smarthome purposes).
My main router is a Netgear R6400 v2 – which has a 1Ghz, 2-core processor and 128 flash/256RAM and “fairness” enabled. I have been finding that connecting more and more 2.4Ghz devices directly to this causes issues: (a) devices to “disappear” – they do not show on the router’s connected devices although they often can still be pinged and (b) the connection to the device may just be dropped entirely. The box for the R6400 clearly says supports 25 devices. But it is not clear if this refers to wifi devices, ethernet devices, or both. It is also not clear if this is per wifi band or both wifi bands. I do not have an exact count, but I am sure I was pushing 25 devices including ethernet.
So I first responded by turning off several of the 2.4Ghz devices bringing the total number connecting to the R6400 directly down to about 15 on both wifi bands. And this “addresses” the issue but is obviously not a long term solution.
In an effort to “solve” the problem, I took an old TP-Link WR841ND with a single-core 400Mhz processor, 4M flash, and 32M RAM and configured it using OpenWRT as an access point with its own2.4Ghz SSID and on a different channel which is connected via ethernet to the R6400. I then started moving many but not all 2.4Ghz devices onto the new SSID. I found that after about 8-9, similar issues arose.
Now, I am not sure if this is because the TP-Link is just too limited to handle the load or if this is an issue with the R6400. Indeed, it is not clear if the issue in total is due to not enough CPU – where a faster or higher core processor would do the trick, not enough RAM – where doubling to 512M would do the trick, or something else entirely.
I had considered going to a mesh system but your write up strongly suggests that they address mostly range and bandwidth issues and I really do not seem to have either of those problems. Perhaps I misunderstand…
Agreeing with you that having a single broadcaster would be better since range/bandwidth is not an issue for me, I have been looking at alternatives to the R6400. But it is just not clear to me how much CPU and/or RAM is needed to address these problems (if that will address them at all). So I have little idea where to turn.
Thanks
The 2.4GHz has very limited bandwidth, David, so if your smart devices constantly upload information, that will kill the Wi-Fi bandwidth on that band fast. In your case, as you described in the email, having multiple broadcasters using different channels is the only way to go. A Wi-Fi 6 mesh system with wired backhauling will help, but how much will depend on the situation, only you will find out. Like I said, those “Smart” devices are evil.
Evil they may be. But I have a lot of them and now, with a new GS-AX3000 in hand and configured, I have them all connecting to the one router on the 2.4Ghz. That’s 27-28 total devices with 22 of them being on 2.4Ghz. They have stayed put and worked well so far. I have also noted that the signal strength of the 2.4Ghz at the farthest point on my LAN is greatly improved using this router. I am sure my issue was not signal strength related, but this is a nice side-effect of the change. I do not know what it is about the new router that makes the difference over my old Netgear. But it does have a faster CPU with an additional core plus 256M more RAM. The performance graphs built into the stock firmware show it is not even breaking a sweat: core 3 is almost never used – however RAM usage is above 60% and that exceeds the total available on the Netgear. Cheers and thanks!
Glad it worked out, David. Thanks for the update. In the end, it’s all about managing them. ๐
I have 20 lifx lightbulbs, 2 nest cams, 5 smart speakers running on 2.4ghz and zero issues. Maybe not enough to cause a problem in a small home.
You already have a separate band for them it seems, as I mentioned in the post. Way to go, P!
Hi Dong, I admit to having already fallen into this trap. I have 15 devices that are exactly as you describe: economical, obscure brand WiFi Smart Home devices. Fortunately when I most recently replaced my router I bought a Tp-Link AX90 so I have separated out the 3 bands and all these devices are on the 2.4GHz band. They are all working ok so far. The only device other than the Smart Home devices on that network is my elderly, circa 2010, Kindle Keyboard. That works ok too, which is good because it is still the best device I have for book reading in good light.
The Kindle doesn’t connect much, Gordon, and it actually has decent Wi-Fi specs. Looks like you’re in good shape! ๐
One thing you forgot to mention is that IoT devices tend not to work well in WiFi 6 environments.
As for Matter, it’s an IP based framework that was created by the Zigbee Alliance, together with Google, Apple and Amazon, and it’s first implemention (and likely the most popular one) will run on WiFi.
I did, Dror. “Wi-Fi 5 Wave 2 and newer” includes Wi-Fi 6, 6E and 7. ๐
As for Matter, it’s Wi-Fi-based but proprietary — the clients don’t connect to a home’s regular Wi-Fi network directly — similar to the case of the Arlo I mentioned.
It’s more than a slow down – these devices tend to intermittently disconnect from the network, rendering them unusable.
The only way to overcome this is to disable WiFi 6 on the band or guest network they connect to – or setup a dedicated WiFi router for them on a different channel.
Or just remove those devices, or put them on a separate band. ๐
I have a netgear mr60, so I cant split 2ghz and 5ghz and there is no mixed wpa2/3. I tried to make my main network wpa3 and guest network wpa2.
And placed my IOT devices on the guest network, however following that the devices stopped working on homekit.
Your Homekit devices are fine, Mahomed — they are not using Wi-Fi. Read the post again. ๐