New user setup questions

  • Hi. I've just replaced my previous wifi system (multiple Airport Extremes and Expresses) with (so far) 2 HDs and a mesh. The 2nd HD uses an Ethernet backbone. I have a few general questions:

    1. If I leave band steering enabled, I find that my iphone's wifi disconnects and reconnects (fairly quickly) as I wander around the house. Is this to be expected with band steering on? Doesn't seem to happen with it off.

    2. Even standing right next to the "backboned" router, if I have a 2.4GHz connection with at least a 90% signal, I can only get up to around 50mbps running the Speedtest app. My Internet connection is 100Mbps. The Amplifi app will show an Rx speed of anything around 130Mbps for that iPhone. If I get a 5GHz connection, I get the full 100Mbps. Why is this?

    3. Is there such a thing as having too many routers? I have another couple to install (both with an Ethernet backbone). Do they "get in each other's way" when they're in relatively close proximity?

    4. My iPhone still seems to hang on to a weak signal for far too long. Should the Amplifi system stop this happening, or is that just the way it is, and it's up to the client to switch to a stronger signal?

    Thanks for any and all pointers.

  • 2.4 GHz connections cannot carry more than about 50 Mbps so that's expected. You need 5GHz for higher speed than that.

    You can't have too many routers, they will mesh just like mesh points will. Of course at some point it won't help anymore.

    In a web browser, go to http://amplifi.lan and log on to your main router using your router password. Enable the 802.11v and 802.11k options. This should give you better handoff between stations. The r option is somewhat flakey with iOS clients in my experience so probably don't enable that.

  • Thank you very much for the quick and helpful response. I hadn't come across those settings. But I can't even see an r option. Where is that? Strange these settings don't appear in the app anywhere (that I could find). After that, you think it will be OK to use band steering again? And would this help with clients hanging on to weak signals for too long?

  • @jao-van-de-lagemaat Oh, also meant to ask if it's normal for multiple HDs to pick the same wifi frequency (happens for both 2.4 and 5). I would have thought they would automatically pick frequencies that didn't clash.

  • Hi @steve-dawson

    1. there is a disconnect + reconnect (hand-off) when roaming between access points. How fast this occurs has been an ongoing issue with Apple devices. If it is fast enough (seamless hand-off) then you shouldn't lose streaming for example.
      There have been some firmware releases where the hand-off period has been quite long, and the phone might change to a cellular link before picking up the WiFi connection again.

    Band Steering tries to influence your device to 5 GHz connection which is typically faster, but typically has less range than 2.4 GHz.
    Band Steering works by delaying the access points response to a 2.4 GHz probe by your device, so if the 5 GHz signal meets your devices criteria for selection, it will choose it before considering the 2.4 GHz signal.

    With Band Steering off, your phone has a relatively equal chance of picking between a 5 GHz & 2.4 GHz signal probe.
    So it really depends on the conditions your phone is seeing once it notices that your current connection is dropping below the threshold it has set to stay connected (which I think is -70dB for Apple).

    If your access points are close enough together that you can hop directly between two 5 GHz signals, then the re-connection time might be different than if you have to go from 5 GHz on one AP to 2.4 GHz on the other.
    With Band Steering off you might more easily go from a 2.4 GHz to 2.4 GHz, but again it depends on your access point locations within your environment.

    1. AmpliFi spec's their 2.4 GHz 802.11n performance as up to MCS23 = 450 Mbps @ 3x3 MIMO.
      A single 40 MHz channel 2.4 GHz stream can go up to 150 Mbps.
      If you are limited to 20 MHz channels then MCS7 = 72.2 Mbps.

    You need to check the WiFi capability of your iPhone (802.11n or 802.11g) and how many streams it can handle.
    Then you need to check if your router is set to 20 MHz channel or 20/40 MHz channels.
    Another thing that may be influencing your 2.4 GHz performance is then other devices using the same band and channels in the area.

    So if you have other Bluetooth devices, or even a neighbor's WiFi router, operating on the same channel then the bandwidth needs to be shared so everything can keep playing together nicely.
    RF noise from things like microwaves and fluorescent lamps can also cause a drop in bandwidth at 2.4 GHz.

    5 GHz is usually less crowded, and thus offers more available bandwidth, but that comes with the trade-off of less range.

    1. I would say 'yes' because it is your device that has to decide when to change connections, and that is often determined by signal strength. You might witness some strange behavior, but again, a lot depends on the environment as well, such the construction materials of the building, how many walls you are trying to pass a signal through, etc.

    I recommend installing one access point (the main router), setting your desired channels and bandwidth for 2.4 & 5 GHz, and then probe the limits of your environment, marking out the boundary of where everything works well.
    Then in or as close to a dead spot as possible that is accessible by your Ethernet Backbone, add your next access point and repeat your performance evaluation, adjusting as you can.

    You may then find turning off/on Band Steering helps or makes things worse.

    Keep adding Ethernet Backbone where possible, and only when you have an unreachable dead spot that you want to cover, add a wireless access point, strongly recommending using a AmpliFi HD Router instead of a MeshPoint HD (search the forums to see reported issues).

    1. It is ultimately up to your device to decide when to roam between access points. You can influence what your device sees by trying to optimize your access point settings and placement within your environment. Band Steering may also be a factor.

    As @Jao-van-de-Lagemaat commented, you can enable 802.11k & 802.11v which allows the router to inform your devices about your network and where might the best access point be to connect to and iOS does support this. It definitely doesn't hurt to try them, but not all devices support them.

  • Hi @steve-dawson - 802.11r was removed from the latest firmware because it was causing issues with some devices, particularly Apple iWatches were not able to connect if it was enabled.

  • Hi @steve-dawson - are you referring to the mesh-points using the same channels for the 2.4 GHz & 5 GHz bands?

    My understanding (which may be wrong) is that since the AmpliFi routers & mesh-points don't have dedicated back-haul radios, they operate on the same channels so they can perform both device connection and back-haul duties.

    There is only one 3-steam 5 GHz radio and one 3-stream 2.4 GHz radio per access point.

    That is why throughput could be significantly degraded on a wireless back-haul mesh-point if both the back-haul and the device are trying to operate on the same band at full or higher speeds.

    The maximum aggregate throughput is 1750 Mbps, which would require using a 3x3 MIMO 80 MHz channel 5 GHz connection + 3x3 MIMO 40 MHz channel 2.4 GHz connection simultaneously (1300 + 450 Mbps) under ideal conditions which is very difficult to achieve.

    Again, this is only my suspicion, and I may be wrong.

    There may be other roaming hand-off issues changing between channels that they are trying to avoid too.

  • @derek-saville Thank you very much for your detailed reply.

    I have enabled 802.11k and 802.11v. It did seem to help, but I've still had some dropouts back to 4g. In both cases, I was walking near an Ethernet-connected HD Router and the iPhone was connected to it over 5GHz. Then the wifi dropped for a couple of seconds, and reconnected to the same router, still using 5GHz. Do I just put this down to the vagaries of wifi and live with it?

    I have also enabled 20/40 width in the main router. It hasn't made any difference to download speeds. Standing right next to an Ethernet-connected HD with 100% 2.4 signal, my iPhone X could still only get up to 50Mbps running the Speedtest app. Does that mean it doesn't support the wide channel? On my Mac, I have the Wifi Explorer app. It still shows 20MHz as the width of the 2.4GHz channels, but I don't know if that means anything.

    I just realised that you have no control over the frequencies being used by Ethernet-connected HDs and mesh points. So do you just have to live with possibly overlapping signals?

  • Hi @steve-dawson - a lot of people, myself included, have experienced the drop to 4G during hand-off, and this is something I believe they are actively working on to improve.
    I assume you are on firmware 2.6.3

    Roaming performance has unfortunately fluctuated a lot over the last few firmware releases.
    Beta firmware 2.7 is being tested and I hope will bring some resolution.

    I don't agree with just 'living with it', but there isn't really anything more you can do other than optimizing your environment.
    Just wait for firmware/software improvements on both the AmpliFi and device side (i.e. iOS).

    Achieving a 40 MHz channel on the 2.4 GHz band can be difficult in some crowded environments.
    I usually go to the FAMILY tab in the app, click on the device I am interested in, and go to CLIENT DETAILS and check to see what connection speeds the device is making (you won't get better than that) and how many MIMO steams are being used.

    You might see the connection speed drop if there is contention and you start bandwidth sharing with other devices.

    To my knowledge you cannot change channels on Ethernet back-haul mesh-points.
    They added on Ethernet Backbone in a later firmware release, so the restriction may not have been lifted or the platform just wasn't meant to support it.
    Again, this is one of the reason why I say you can have too many access points too close together.
    With a lot of devices, if access points are 'running into each other' then they have to share that channel bandwidth.

    Ideally I think you should be able to use a different channel when Ethernet back-haul is enabled, but that might cause other roaming issue they aren't ready to debug yet.

    My suspension is that the AmpliFi devices are somewhat limited by only having 2 radios and the one 1 dual-band tri-polarity antenna.

    This is a design trade-off to make them small and 'cute' versus bigger access points with more antennas and dedicated back-haul radios.

    One testing website I like believes "Wi-Fi Systems live or die on the strength of their backhaul bandwidth. It's usually the first test I run, because if the backhaul ain't good, I won't waste my time trying to figure out why the other tests are bad."

    Shouldn't be an issue with wired Ethernet backhaul, but if the system is designed and tuned for a less capable wireless backhaul, then the benefits may not be fully realized yet...

  • Yes, I'm on 2.6.3 all round.

    My environment is not crowded. No other networks in sight most of the time. The only crowding is from my own Amplifi gear! With 40MHz width selected for 2.4, I'm seeing no difference in performance. The likes of the iPhone are reported as about the same speed, and mimo 2 x 2. Any more ideas as to how I can boost 2.4 speed? Not that it's that important, just trying to wring the most out of this.

    I think the inability to fix channels on the routers when using an Ethernet backhaul is a real drawback. Each device seems to pick its own channels (they don't all follow the main router's ones), and it appears to be random. There will obviously be radio channel overlaps between routers (otherwise there'd be dead spots), so the routers picking the same channels in many instances won't be helping things at all.

    Thanks again for your thoughts...

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