Indoor Wi-Fi Roaming with OpenWRT
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On iOS, equal channel with correct ESS will switch liberally. On Android 14+ with Broadcom chip it will start conservative, then switch liberally after the first poor signal switch-over event, up until disconnection.
Android (Pixel/Moto) will never switch (even with K/V) on large network activity, only VoIP/video call. It depends on vendor implementation. [0] I use "dp.logcatapp" log reader while roaming, "com.android.location.fused" can be used to show score and current load.
Samsung is known to push protocol support early: 802.11r in 2013, 802.11w 2015, some models do not use Android's default connectivity manager.
To add, WPA3 with 802.11r is known to have issues on Apple hardware before 2021 on all iOS versions, many Android devices, especially smart TVs don't support it, will not connect or are unreliable (protected beacon frame), can be searched in buried report results at OpenWrt forum mega threads and Ubiquity. WPA2+FT and forced MFP with a long password is a safe alternative. 802.11r use PMK push on WPA3 compared to WPA2, which was known to be problematic on older hardware.
802.11K/V is more suitable for campus and load balancing, tuning it based on RSSI and station metrics is very difficult, enterprise hardware rely on network traffic and air time.
[0] https://source.android.com/docs/core/connect/wifi-network-se...
I need my TV to rapidly switch APs in very heavy load wide area networks with thousands of devices while I'm cruising through the venue with my motorized couch and entertainment system.
Now I want to actually build that for GPN24 next week. Wouldn't use AndroidTV for that though.
Not sure if roaming is actually the fix for this problem. For whatever reason my Ring cameras just love connecting to the worst and most far away AP in my house.
I had to solve a similar issue for some crap IoT lights that would join the incorrect AP after a power cut every time.
> https://community.ui.com/questions/Lock-Client-to-Specific-A...
That can mean that the portable wifi speaker-widget (which itself doesn't need much bandwidth) might go from working fine on the back deck or well-enough about anywhere else in the yard, to not working at all outside.
Which is normally a good thing to push the clients to roam to a better AP, OR you walked out of the building and want you phone to disconnect. But yes, does impact overall coverage area size.
Meanwhile: As a practical matter, shrinking coverage means "Hey, honey! I fixed the TV!" gets met with a response like "Oh, so that's why I can't listen to Audible on the veranda anymore!" :)
Obviously only if your honey is the type that enjoys being experimented upon (So long as it isn't mean, I like thoughtful attention like that, but some might not).
With 802.11r on, things would disconnect for 60+ seconds before reconnecting. It was a constant frustration of "arrrrrrrggghhhh fucking connect damnit I'm standing a meter in front of the AP can't you fucking see it fuck fuck fuck just connect, it's right THERE, connect NOW, arghhh" and then it would completely disconnect (no wifi found) and then reconnect a minute later.
With 802.11r off things just roam smoothly. I guess the people who inventned the tech didn't test it thoroughly enough.
Unless they've reimplemented the whole damn thing since like 2018 or so, UniFi is OpenWRT with the serial numbers filed off, and UBNT is known to be not especially great at having good software on the APs. I had a square UAP-AC and then an AC-LITE and an AC-LR all running the official software for several years. While the management GUI seemed like it'd come in handy if you had to manage like a hundred APs, I wasn't impressed with either official support or the rest of the software.
I've been using the U6-Pro backed by UCG-Max and couldn't be happier.
Yes - the software running on the standalone APs is still basically OpenWRT wrapped with a management layer. But UniFi has grown to a much larger system. All the router boxes are running Debian, for example (even those with a built-in AP).
I agree. The AC-LR and AC-LITE were way better than the -AC. That guy ran extremely hot and was dogshit at multicast. In contrast, the -LITE and -LR merely ran notably hot and were merely intermittently bad at multicast.
Loading up OpenWRT on the -LR and -LITE made them work quite a lot better (though -obviously- they still ran just as warm). Ditching them for the OpenWRT One was even nicer.
You're at the mercy of UniFi not having any show stopping bugs (haha), the client device supporting 802.11r or at least tolerating it, and the interaction between UniFi and the client not having any show stopping bugs.
It's an interesting setup, looking forward to an update.
So it's fine if the user doesn't have a shaft between them and the AP. When they move so a straight line from the device to the AP crosses through a lift shaft, they enter the wireless "shadow" cast by that shaft, preventing them from contacting the AP. When they take another step forward the device might "come out of the shadow".
This is a difficult situation to deal with in roaming, where the visible AP set changes rapidly as the user moves a small amount.
TL;DR: I'm pretty sure the parent you're replying to "got it" and you didn't understand what they were trying to say.
Fast roaming has not, does not, and never will require APs be on the same channel. Only the SSID and password needs to match.
Setting them to the same channel will cause the APs to interfere (when they can't "hear" each other) or block each other from transmitting, or both. You set APs near each other so they are on non-overlapping bands. Always.
This is basic WiFi networking 101
> Samsung is known to push protocol support early: 802.11r in 2013
802.11r was released in 2008 and rolled into 802.11-2012.
Also, the iPhone 5S (2013) has 802.11r support.
There were no mentions of requirements for 802.11r in the comment. You removed "much faster than K/V." from the quote. "only" was referring to 802.11r exclusively. You can have the same results with different channels with K/V, provided that the clients support it as the rest of the comment mentions.
802.11r-only on different channels is ineffective for devices without K/V, since the reductions are insignificant.
You will be shaving 100ms from a 700ms delay on scan and association, compared to no-scan association which is around 20ms, hence the 75ms note.
And even then, FT is only needed for short buffer streaming like VoIP and VoWiFi. It's more important for WPA3, since handshake roundtrips are even longer (~300ms) which can degrade video/voice internet calls with a lengthy time to recover and complete silence for second or two on VoIP, it's not really needed for the average user back when WPA2 was standard.
Android and iOS will first scan on the same frequency, then rotate through the channels, which is now even longer on 6Ghz capable devices with the total number of channels.
The transition time is significantly faster with equal channels on most hardware, this is where 802.11k helps with different channels, especially in iOS. Without it, they cache scan results provided that the farthest AP is detected, this rarely happens since the scan time is so short.
Scanning different channels while connected causes large amount of jitter on station optimized WiFi SoCs, affecting VoIP on mediocre connections while the user is moving and actively losing signal, so its done as quick as possible, often missing many beacons. They can scan longer on the same channel without degradation. [0]
Without K/V, iOS/Android goes to the extent of doing frequent rescans on low network activity on body movement, you can install a Wi-Fi diagnostic profile to view the current activity on iOS, logcat on "fused" for Android.
The suggestion doesn't bash on 802.11k/v, it's just a compatibility alternative, considering that very few clients support it, let alone off the shelf consumer AP support.
> Setting them to the same channel will cause the APs to interfere (when they can't "hear" each other) or block each other from transmitting, or both. You set APs near each other so they are on non-overlapping bands. Always.
> This is basic WiFi networking 101
This is only true under large air time traffic and in large scale indoor setups. Not satellite APs that are far. Qualcomm, Mediatek and many systems implement their own spatial reuse technology. WiFi 6+ introduces BSS coloring for channel width overlaps to further improve speeds on mixed traffic, not to mention the generally low penetration / TX power of 5Ghz+ on SNR.
>> Samsung is known to push protocol support early: 802.11r in 2013
> 802.11r was released in 2008 and rolled into 802.11-2012.
> Also, the iPhone 5S (2013) has 802.11r support.
The Samsung line in the comment was referring to Androids, many Android didn't support these until 2020, some non-flagship still don't (disabled), Samsung was notable to include it early, there are three paragraphs underneath referring to old phones and smart TVs, both Androids. It is not enabled by default on many off the shelf APs for these reasons.
[0] https://support.apple.com/en-sa/guide/deployment/dep98f116c0...
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Is that really true? We make sure all our APs are on different channels to prevent interference.
I haven't had luck with the roaming extensions; when I run them, some of my devices won't connect or won't stay connected and it's a pain to monitor. I guess I could run a different SSID with roaming enhancement, but effort.
Not sure if they finally got around to making the BSSID selection algorithm a bit smarter or whether all my access points just support active steering at this point, but I haven't seen this in the past couple of years.
My workaround for part of that is using many SSIDs.
A. The SSID that covers both bands, in all areas
B. Two more SSIDs, one for each band -- again, used in all areas
C. Another SSID just for the AP in the garage (which also has A and B SSIDs)
It has some advantages: I like being able to set a portable device to SSID A. These things usually figure it out well-enough while moving around. When someone visits and asks for wifi access, I give them SSID A. It works; it's just not always perfectly ideal.
It also prevents fixed devices in the garage from deciding to use APs in the house; it never works well for them when that happens. (The opposite problem hasn't been observed to be an issue yet.)
And it lets me decide whether any device is able to use 2.4 or 5GHz, in the usual way of having per-band SSIDs. If my TV streamer weren't plugged in with ethernet, then I'd set it to use the 5GHz-only SSID.
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A big downside is that it's ugly. Another is that the per-device config is spread out amongst all of the devices instead of centralized, but that's not so bad: I just make the SSID decision at initial device setup and forget about it.
What are the nuts-and-bolts reasons that would make 5 perform worse?
Beacons repeat every 100msec. So you're already wasting up to 40/100 of airtime for management/misc frames
Wifi is a shared half duplex medium
Previously, I've never thought much about the airtime required for beacon transmission, nor that it increases as SSIDs are added.
Thinking about it now, I can see some ways to improve the cost of these SSIDs.
Like, increasing the minimum speed/excise old protocols (I probably don't need 1Mbps 802.11b at all in 2026 and can't think of any strictly 802.11b-only device that I've ever owned) to decrease the time that beacons use.
That seems like one obvious improvement that should be is free of other tradeoffs.
There's a few other things I can think of, but I'm not done thinking about it yet. :)
That hasn't been my experience at all. Checking my current network status, I've got 24 devices connected to 5GHz and only two devices (my two Nest Doorbells, for whatever reason) connected to 2.4GHz that also supports 5GHz.
My N=1 vs your N=1.
Because the 6 devices on 5Ghz: laptops and smartphones.
The rest are "smart" devices that work perfectly on 2.4Ghz.
About a decode ago when debugging networking issues in an office, we had the observation that Apple hardware holds onto access points for dear life. Everything else would roam fine, but Apple would stay connected to distant access points with awful signal as if Steve Jobs' life depended on it.
The signal has to drop below -70dbm for ios and -75 dbm for macos for the devices to consider roaming. Additionally, the difference between the two AP has to be 8db for ios and 12 db for macos.
https://support.apple.com/guide/deployment/wi-fi-roaming-sup...
IMHO, these are good defaults. Apple devices are optimizing for stability over the “best” possible signal.
What you might consider awful signal difference between the two APs might not be. (e.g. a mac device at -75dbm need to find another AP with -63dbm or better.)
What difference does the presence of legacy devices make? Is the intent to isolate them from modern devices from a network perspective? Then create a separate SSID on both 2.4 and 5 GHz for modern devices.
I can't think of any legitimate reason for split SSIDs anymore. Linux clients used to be pretty bad at preferring 5 over 2.4 GHz if RSSIs were both excellent but 2.4 was slightly better, but I haven't seen that in years.
Plus I still have some esp8266-based widgets that I made which only operate on 2.4GHz.
5ghz is important if you are interference limited. The lack of wall penetration and short range become benefits.
2.4ghz provides very poor performance in my condo due to the 30 different SSIDs I can see from my lounge room.
5 GHz has much less of that, but big parts of it have weather radars as a primary user, with APs being required to detect and avoid any channel where they can detect one.
Different networks / vlans / firewall rules.
I'm responding to the question about why you might split SSIDs. SSIDs don't have anything to do with frequency necessarily, morso network segregation.
Also:
> What difference does the presence of legacy devices make? Is the intent to isolate them from modern devices from a network perspective?
Yes. Old devices can only use limited data rates and they will drag down the throughput of other devices on the same channel. Some controllers or APs allow you to limit to lowest data rate you will accept a connection from.
Sure, I was only talking about splitting by bands as I thought that's what this entire conversation is about. Of course there are plenty other reasons to have more than one network in the world :)
> Old devices can only use limited data rates and they will drag down the throughput of other devices on the same channel.
They will do so regardless of which AP or SSID they are connected to, though, as the channel is a shared physical medium.
If the goal is to isolate slow/old devices from modern ones, that can be done regardless of the band.
In a multi-ap setup you can isolate those 2.4ghz devices to their own, short range said that allows very permissive datarates. Then everything else gets 5ghz or 6ghz with mediumish output power and restricting the lower data rates. This prevents clients that move to the edge of the coverage zone from hitting lower data rates and dragging the whole channel or SSID or both down.
It just depends on your setup, number of APs, type of devices, device demands, etc.
Which is a bit sad, but also seems like it would allow this use case perfectly (assuming this was done on purpose and not just an oversight).
I think so, yes. My OG Nintendo Switch connects to the PSK SSID on my two OpenWRT Ones that's using what OpenWRT calls 'sae-mixed' encryption mode. My PCs (using ath9k and rtw88_8822be drivers) and my Pixel 5a connect just fine to my EAP SSID that's using the 'wpa3-mixed' encryption mode.
wpa_supplicant says that the PSK SSID has "SAE" in two out of three of its supported operating modes, and the EAP one has "EAP-SHA256-CCMP-preauth" in one of the two. [0] I assume that means that they support WPA3 operation, but I don't know for certain. I'm somewhat ignorant about WPA3, and am profoundly ignorant about WPA3-EAP.
[0] I'm assuming that the "/"-separated list that comes after the "WPA2-" bit in wpa_supplicant's scan results is a list of what I'm calling supported operating modes.
To me at least, the gold standard for a large home is a standalone cable modem or ONT connected to an x86 PC that serves as home server and router, and as many ceiling mounted APs as necessary to ensure good WiFi coverage. No cloud, apps, or proprietary software anywhere. With such a networking backbone it is also easy to integrate self-hosted security cameras and other appropriately hacked IoT devices.
Great write up, good information to share. This really is such an important next step for many people's wifi and it's documentation is pretty so-so.
* https://www.omadanetworks.com/us/business-networking/omada-r...
Running Omada on my Windows Server was painful (doesn’t really run properly as a service, software updates are a chore), but since I moved it to run on Proxmox using a super simple LXC image (I maybe got terminology wrong here) it’s been very nice.
Supposedly I should have excellent roaming between the APs, but I’m not sure how to check. Certainly, walking from one end of the house the other while on a Teams or WhatsApp call on my phone has maybe only a super minimal amount of time that I might not hear the other person (sub second for sure, if at all), but mostly I don’t notice.
Any combination of 802.11r and k/v seemed to just cause my phone's connection to drop for minutes at a time when moving around the house.
I wish I could remember my exact solution for you, I believe I just turned off 802.11r and k/v, set channel selection to automatic, and undid any manual or automatic power tuning.
I've also moved primary mobile devices to 6ghz & putting in 10gig fiber for stationary devices.
What's a good off the shelf multipoint wifi system these days? I have Amazon's Eero right now and it's ok.
I'd love to go back to my linksys wrt54 roots but that's not in the cards currently..
The only headache has been setting up a Canon printer -- it doesn't know what fast roaming is and won't prompt for a password if it's enabled. You must disable that first, connect the printer, and then turn it back on.
The main downsides to Eero are the cloud requirements and limited configurability - if those aren't a problem for you it's a very nice system.
https://store.ui.com/us/en/category/cloud-gateways-wifi-inte...
And if you need more coverage or other networking gear at a later point, you can just tack on another access point or a switch or something, and it all works together seamlessly through a single interface
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Hah. I expect to see a lot of more of this kind of thing in the future, at least until someone works out how to integrate LLMs with a more structured approach to AI. We can't get away with just asking the prediction machine to "do what I mean, please and thank you."The fact that so many people are now running around with "agentic" software that fundamentally can't distinguish between their own "thoughts"/rules and untrusted user input doesn't turn a meme into malware.
Token predictors by themselves are fundamentally insecure, and cannot be made secure without a strong semantic world model. It's like `eval`-ing everything, or auto-coercing strings to objects or function calls, vs having a strong static type system.
Am I wrong?
If you want multiple SSIDs, roaming, daily neighbor scanning and auto channel selection, etc, but don't like to spend hours tinkering with your equipment beyond the physical setup, then Ubiquiti UniFi equipment is great.
I stopped recommending UniFi around 2020 (several of their best engineers had left, and they made some dumb choices), but IMO they're back to being a decent choice. And I appreciate that they're become a one-stop solution for all home/SOHO as well as mid size enterprise IT needs.
You can even use the mobile apps over direct connection, with local auth and no cloudy relay required.
This wasn't hours of tweaking. Well, over almost a year, maybe two hours, but no more than that.
For my needs unifi was worth it to not have to deal with OpenWRT again, or worse, stock firmware on consumer APs.
Amusingly, I was quite willing to put up with a day or two of tinkering and puzzling over the -occasionally godawful- docs to never have to deal with Unfi and the rest of UBNT's software ever again. Even my recent move from my OpenWRT-"powered" UAP-LR/LITE to my OpenWRT Ones required only a little bit of fussing with the configs I copied over from the -LR and -LITE... and that was because of the difference in device names between the UBNT hardware and the One hardware.
By lucky chance, while he set up usteer, he modified DTIM to 3 thus fixing the fast transition roaming, which doesn't work well on default openwrt because of DTIM. Especially Apple devices really hate DTIM=2 (they need the extra off-time given by DTIM to properly scan the other channels).
I do know what Apple devices "like" (it's kind of my thing, hence the domain name).
This "here's a neighbor table, disassoc and fuck you&good luck"-method we must use right now is just super painful. It's super complicated to build reliable networks that way.