General Does iOS prefer 2.4 or 5 Ghz band?

Discussion in 'iOS 8' started by Morac, Jan 24, 2015.

  1. Morac macrumors 6502a

    Morac

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    Dec 30, 2009
    #1
    I'm trying to determine whether iOS prefers 2.4 or 5 Ghz when all things are equal.

    The reason I ask is that I've read that Apple recommends using the same SSID and security settings for multiple Wifi networks and that people have reported that iOS prefers 5 Ghz in that set up, but I haven't found that to be the case.

    My setup is that I have a Linksys E3000 which is dual band. The 2.4 Ghz band is set up b/g/n while the 5 Ghz is set to n only. Other than that and the channel the settings are the same. Both use WPA2 personal.

    For a long time I gave the 2.4 and 5 Ghz networks different SSIDs so I could choose which band to join. The reason being that the 5 Ghz one is significantly faster (at least 3 to 4 times) than the 2.4 Ghz one and there are many neighboring 2.4 networks which cause interference. Also there are g devices on the 2.4 network. The 5 GHz one doesn't have the range that the 2.4 one does.

    With that setup my iPhone 5s tends to jump on to the 2.4 network and stay there, but my iPad Air 2 will stay on the 5 one if I put it there.

    I recently got a WeMo which for some reason only allows local connections on the same SSID (have no idea why), so if my devices are on the 5 Ghz network, they behave as if I'm not home. To get around this I set the 2.4 and 5 network to the same SSID, assuming that the 5 network would be preferred, but that's not what I'm seeing.

    With my iPhone and iPad sitting next to the router, both join the 2.4 network. If I turn Wifi off on the iPad and back on, it will join the 2.4 network again, but will usually switch to the 5 and stay there until I get about 20 feet from the router at which point it jumps to 2.4 and stays there even if I move back to being right next to the router and sit there for 5 minutes. Basically the only time it joins the 5 Ghz network is if I turn Wifi off and on, which is extremely inconvenient.

    The difference in speeds on the iPad can be as high as 5 Mbps compared to 200 Mbps, so obviously I'd prefer it to be on the faster 5 network.

    The only info I've found from Apple is http://support.apple.com/en-us/HT202831 which states that all things being equal iOS prefers the stronger RSSI, but stronger RSSI doesn't mean faster or even stable, depending on interference. 2.4 almost always had a stronger RSSI because of it's very nature of the frequency.

    Any ideas why iOS is preferring 2.4 for me when others say it prefers 5 Ghz? Is it simply RSSI strength? If so iOS would never join a 5 Ghz network if a 2.4 one was nearby.
     
  2. Gav2k macrumors G3

    Gav2k

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    Jul 24, 2009
    #2
    Your 2.4ghz network will always be the stronger of the network signals to any device.

    Personally I save my 5ghz network and delete my 2.4ghz network because through testing I know how far my network reaches.
     
  3. Morac thread starter macrumors 6502a

    Morac

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    #3
    Unfortunately that doesn't solve my current issue which is that WeMo devices require iOS devices to be using the same SSID otherwise local control is disabled. I realize that's a WeMo limitation, but it's still an issue.

    I don't suppose picking up a 5 ghz WAP and giving it the same SSID as the 2.4 network would help? I could also lower the power on the 2.4 network, but that just means I wouldn't be able to get Wifi in certain areas of my house.
     
  4. ZEEN0j macrumors 6502a

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    #4
    This is why I have two routers. The bathroom/kitchen wall between my bedroom and living room kills my wifi signal. 2,4 and 5ghz with different ssid. And connect all compatible devices to 5ghz. As soon as the signal is two low to one router it auto connect to the other.
     
  5. sunking101 macrumors 603

    sunking101

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    #5
    With my old i4 and i5, and now my 6+, WiFi access seems to give priority to my pc and Android tablet. Whenever I'm online, my iPhone slows to a crawl if the other devices come online. I've always wondered why that is because the other two devices get bandwidth with no problems.
     
  6. Morac thread starter macrumors 6502a

    Morac

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    #6
    Well it turns out in my case I was wrong about the WeMo. It doesn't require being on the same SSID to control it. It requires that the iOS device be on the same SSID that it was on when"remote access" is enabled, otherwise the app goes into "away mode", which is just stupid.

    I've left the 2.4 and 5 Ghz networks with different SSIDS and simply disabled remote access for the WeMo app on my iPad Air 2 which lets it work on either SSID. The iPhone 5s, I've registered remote access with my 2.4 Ghz SSID, since it has a tendency to jump to that SSID anyway.

    The iPad Air 2 will stay on my 5 GHz SSID if I put it there manually. It will switch to 2.4 Ghz eventually, but at a much farther distance than my iPhone 5S will. Basically it will stay on 5 Ghz anywhere inside my house, which makes me wonder why it frequently jumps to the 2.4 Ghz band if the SSIDS are identical.
     
  7. Syndicate0017 macrumors 6502

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    #7

    This is how access points work. As far as your device is aware, when it sees an identical network name with identical security, it will roam to a more "preferable" access point based on minimum RSSI threshold. It doesn't care if it's 5 ghz or 2.4 ghz. If the names and security are the same, it will roam once the device thinks it best to roam.
     
  8. I7guy macrumors G5

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    #8
    Read up on wireless protocol. I just bought a netgear r8000. It's a beast of a router with three radios and auto groups devices on a per radio basis for best performance. And the coverage is outstanding.
     
  9. sbailey4 macrumors 68030

    sbailey4

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    #9
    Best to set the SSID's the same. Then the device will roam without intervention based on best throughput. Not just RSSI. With separate SSID it will hit the 2.4 and most likely never go back due to the stronger signal. Setting both the same it seems to prefer 5ghz but if get out of range it switches to 2.4ghz automatically then switches back when 5ghz is strong again. Works great that way for me. Also here is more info on the subject from a Apple engineer.

    I tried separate for a while but found 90% of the time if I went upstairs or outside or whatever I would have to manually join the 5g again when back downstairs or inside to get 5G back. Same SSID solves that issue and iPhone seems to prefer 5ghz when its available.
     
  10. Syndicate0017 macrumors 6502

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    #10
    Not sure I agree that setting the SSIDs the same is the best practice. Especially if your goal is to limit roaming to the 2.4 ghz band. The easiest solution to this problem would be to add a second dual band access point. You could then even turn down the TX power on the 2.4 band on the second AP if roaming is still an issue (though if you placed the AP ideally it shouldn't).
     
  11. geoff5093 macrumors 68000

    geoff5093

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    #11
    If you set separate SSIDs, when you arrive home your phone will pickup the 2.4GHz network first, and since they are on different SSIDs they will never switch. If you want to use 5GHz, you'd have to toggle Wi-Fi off and on.

    As far as your other device requiring them to be on the same SSID, I don't believe it will work if one is on 5GHz and one is on 2.4GHz, even with the same SSID, as they are essentially two different networks, despite having the same name. If it doesn't work with different network names, it won't work with the same name if they are on two different bands, the name has nothing to do with it.

    They should prefer 5GHz, even though it's a weaker signal, but I've also noticed at times it stays on 2.4GHz. Usually it will stay there when first toggling Wi-Fi off and on, and then move to it shortly after negotiating.
     
  12. sbailey4, Jan 26, 2015
    Last edited: Jan 26, 2015

    sbailey4 macrumors 68030

    sbailey4

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    #12
    But why would you want to limit 2.4 ghz if that is the best option at the moment. 2.4ghz with strong signal will be better that 5ghz on very weak. Setting 2 separate SSIDs (networks) you will still see it switch to the 2.4 network when it needs to but it will never switch back automatically. You will have to manually disconnect/connect to the 5g network again. Setting both 2.4 and 5 SSIDs the same it does switch between bands on the same network for the best throughput and is all automatic. My iP6 stays on 5g 99% of the time but when I am in an area with poor signal it will switch and never know it unless you look. Then it switches back when 5G is strong again.
     
  13. Syndicate0017 macrumors 6502

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    #13

    The OP doesn't want his 5S roaming to 2.4 ghz because there are lots of wifi networks around him and the band is congested. The 5S doesn't seem to gracefully switch between 5 ghz and 2.4 ghz as some of apple's newer devices.
     
  14. sbailey4 macrumors 68030

    sbailey4

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    #14
    Don't believe that's the case. "Any ideas why iOS is preferring 2.4 for me when others say it prefers 5 Ghz? Is it simply RSSI strength?" Otherwise the solution is just name them different and ONLY join the 5ghz ssid. (Forget the 2.4 ghz one in network settings) It would never jump to it then. Supposedly Apple devices connect to wifi based on the preferred order. So setting the same ssid would eliminate that issue as well. Never had the 5s so cant comment on why it would not switch. The iP6 does fine. The link I provided to the other article from an ex Apple engineer stated this:

    "Apple devices choose networks by your preferred order. Period. If you have multiple networks of different names your Mac or iPhone will always choose the first in your iCloud-synced "Preferred Networks" list even if this one isn't going to give you the best bandwidth. If you have the network name/SSID the same then it will chose the radio that it predicts will give the best throughput (which isn't always the one with the best signal, but that's an even geekier discussion you can hear in the show). Make all the Wi-Fi networks in your home the same. Your life will be better for it."
     
  15. Stuke00 macrumors 68000

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    #15
    5Ghz is my preference. I have done speedtests on both. On my 2.4Ghz, I only get 12-15MB from my internet. On the 5Ghz I will get full 90-100MB.
     
  16. sbailey4 macrumors 68030

    sbailey4

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    #16
    What device? 5G def is typically faster but the range is not as good as 2.5. Also that much difference sounds like maybe you have 802.11AC router and maybe iPhone 6/6+. Wireless AC only runs on the 5ghz band.
     
  17. Morac thread starter macrumors 6502a

    Morac

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    #17
    Does iOS prefer 2.4 or 5 Ghz band?


    I read what that engineer said, but from my experience what he said doesn't match up with what I'm seeing if I set the SSIDs the same. My iPad Air 2 definitely prefers the highest RSSI, which is always the 2.4 Ghz network, despite interference causing that network to have about 25% the bandwidth of the 5 Ghz network. Even when I'm sitting right next to the router, the Air 2 will still pick the 2.4 GHz network unless I toggle Wifi off and on and wait there for awhile. I've not seen it switch back to the 5 Ghz network on its own when the SSIDs are the same. I don't know if that's a bug in iOS 8 or just the way iOS works.

    The speeds on the 5 Ghz network are better virtually everywhere in my house, so having two different SSIDs work better to keep my Air 2 from switching to the slower 2.4 Ghz network.

    ----------


    The part that's never mentioned is how does one set a preferred network if one doesn't have a Mac? There's no way to do so in iOS. From what people have gathered iOS, assuming the same security and RSSI, iOS picks networks alphabetically.

    Apple's own support article mentions the order it picks networks and bandwidth isn't mentioned at all, only security and RSSI.

    http://support.apple.com/en-us/HT202831

    That seems like a flawed method as it means iOS prefers a strong, but crappy signal over a weaker, but faster one.
     
  18. Stuke00 macrumors 68000

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    #18
    I do have a 6 on an AirPort Extreme.
     
  19. Grayburn macrumors 68000

    Grayburn

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    #19
    Mine seems to. I was in my sons bedroom the other night and my 2.4 Ghz usually dips out in there and it immediatly asked for the password for my 5 Ghz band, which reminded me that i hadn't put it back in after a recent restore.
     
  20. Syndicate0017 macrumors 6502

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    #20

    That's not really switching. If the 2.4 band drops out in there, then that means it started looking for another known wifi network. The transition I'm talking about is switching between 2.4 and 5 when both are in range. Apple states that their devices should prefer the 5 ghz band. And that doesn't always seem to be the case. Mostly once the 5S switches from 5 to 2.4, it is stuck and will not switch back to 5 until you turn off wifi and back on.

    Unrelated, but how does your 2.4 ghz drop out there and your 5 ghz penetrates? Seems quite backwards.
     
  21. Grayburn macrumors 68000

    Grayburn

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    #21
    You tell me, i don't know myself:confused:
     
  22. sbailey4 macrumors 68030

    sbailey4

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    #22
    That is different. That will happen when there are 2 SSIDs (networks) and you have to connect to one or the other. Problem with that setup is typically when it switches networks due to low signal it will never switch back without manual intervention unless the other network gets low. I suspect you have it backwards though and your 5g is what dips out. 2.4ghz range is better than 5ghz so it would be rare that you cannot get 2.4 but can get 5. Setting both bands to the same SSID is what we are discussing as an option to that. That will change to whatever band, 2.4 or 5, without intervention. Apparently some devices are having trouble with that transition though it seems (iPads?). The iPhone 6 makes the transition flawlessly to 2.4 when needed then back to 5g when its available again all on the fly. Certainly no setup works best for everyone and conditions change how someone should setup their network for best results. But typically the same SSID is a good setup and provides the best coverage with the least amount of intervention.
     
  23. sbailey4 macrumors 68030

    sbailey4

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    #23
    Probably a bug. There seems to be known wifi issues with iOS8.

    I have heard that the first network you connect to gets priority. If that's the case and you have 2 SSIDS maybe forget the networks, then join them in the order of preference. That may make iOS connect to your preferred network when both are in range. Cant say 100% on that one but at one time I had 2 routers (2.4ghz only) with different SSIDS and my devices seemed to connect to the first one I joined when I would come home from being away from the network. Could be coincidence or some other variable since they were 2 different routers. May be worth a shot to try. Interesting I never heard the alphabetically order but anything is possible. That would almost make since :)
     
  24. spaceballl macrumors 68030

    spaceballl

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    #24
    depends on which iOS device you have... I have always used 2.4ghz, but with the 6 / 6+, if you have an AC router, you're probably best off on the 5ghz network. Rock solid now.
     
  25. philbake1 macrumors newbie

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    Feb 16, 2017
    #25
    --- Post Merged, Feb 16, 2017 ---
    I have the same SSID, and a very strong 2.4ghz signal on ch 6, and a moderate 5ghz signal on ch 149...my Apple devices always seem to default to the 5ghz option.
     

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