Unable to connect to WIFI

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  • HenGus
    Automated Home Legend
    • May 2014
    • 1001

    #46
    Originally posted by bjb View Post
    Just wanted to add to this thread that I couldn't get the Evohome controller to even see my wifi when it was on channel 12, but moving the wifi to channel 11 brought it all back working again.

    This may be because the USA only allows up to channel 11, and there doesn't seem to be a way to configure the Evohome to know it's in Europe. It was frustrating until I figured it out.
    The Honeywell server knows where your device is located; that said, I am not sure what that has got to do with home network wifi channels which are usually a router function. In the UK, Channels 1,6 and 11 are normally chosen to avoid co/adjacent channel wifi interference. My auto-channel changing router (a Fritz!Box) will normally chose one of these channels. In the 5 years that I have used a F!B, I have never seen it default to Channels 2, 3,4, 5, 7, 8, 9, 10, 12, or 13 - even when these are showing no other networks in use.

    Last edited by HenGus; 30 October 2016, 09:56 AM.

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    • paulockenden
      Automated Home Legend
      • Apr 2015
      • 1719

      #47
      Many devices that originate in the US can't connect on Channel 12. Early Kindles were the same.

      I can't find the original article I wrote about it, but helpfully someone has copied it into an Amazon review:



      P.
      Last edited by paulockenden; 30 October 2016, 10:31 AM.

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      • DBMandrake
        Automated Home Legend
        • Sep 2014
        • 2361

        #48
        Originally posted by paulockenden View Post
        Many devices that originate in the US can't connect on Channel 12. Early Kindles were the same.
        The main reason for this is that it's often too difficult on a small embedded device that is sold world wide (either with or against the manufacturers consent) to reliably figure out what country it's currently located in, so the manufacturer chooses to simply use the lowest common denominator which is the US channel 1 to 11 configuration, so that they don't break the regulations in other countries.

        There is a standard that allows a client device to work out what country it's in by monitoring the "country code" field of broadcasts from all nearby wifi base stations it can hear (eg including your neighbours) and this technique is used by some Apple devices.

        The idea is that if it detects any wifi base stations transmitting a more restrictive country code (such as US) it will assume it is in the most restrictive country channel wise and disable access to the additional channels.

        Unfortunately what that means to us in the UK (who can use 1-13) is that it takes only one nearby wifi base station to broadcast a US country code (for example a device that was grey market imported from the US, mis-configured etc) and all Apple devices within range will suddenly ban the use of channels 12 and 13.

        So if your own router is set to 12 or 13 your Apple device might have been connecting happily on those channels, a neighbour turns on their grey market imported US router and your Mac or iPhone will drop its wifi connection and refuse to connect to channel 12 or 13 for as long as that other router is broadcasting because it now assumes it is in the US were those channels are not allowed.

        From time spent doing tech support this is a surprisingly common problem and it's one reason that the "auto" channel option in most routers will not choose 12 or 13 even in the UK. You'll only run into this issue if you manually set your router to channel 12 or 13.

        While its nice to have those two extra channels in the UK in theory, in practice because there's only 3 non-overlapping channels from 1 to 11, with most people using 1, 6 and 11, using 12 or 13 doesn't really buy you anything because they still overlap with channel 11, and many devices, even those sold in the UK will either not support 12 or 13 at all (apparently the Evohome) or will support it but be vulnerable to the country code detection issue above. (Mainly Apple devices as not many other manufacturers use this country code detection technique)

        In short, don't use 12 or 13 unless absolutely necessary. More often than not it will cause you problems.
        Last edited by DBMandrake; 30 October 2016, 10:59 AM.

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        • rotor
          Automated Home Guru
          • Aug 2015
          • 124

          #49
          Only ever use channels 1, 6, and 11. That's pretty much it. Follow that one simple rule, and you will optimise your 2.4GHz Wifi experience.

          Good summary on this Super User question:

          I understand that 2.4GHz Wi-Fi channels overlap, and that the most popular non-overlapping set of channels in the US is 1, 6, and 11. Generally, my signal strength on channels 1, 6, and 11 are much


          Cisco tested this. The result is that if you use an overlapping channel (anything other than 1,6,11), you get terrible performance and you make everybody else's performance worse. The problem is that any time an AP on the overlapping channel broadcasts, you get stepped on. And because the channels overlap rather than coincide, other network's transmissions are seen as noise, not signal, and don't trigger the bandwidth sharing built into the design.

          Non-overlapping channels (1,6,11) work better than overlapping channels. With overlapping channels, you step on each other and can't do anything about it. With non-overlapping channels, you see each other and share the bandwidth.

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          • bjb
            Automated Home Lurker
            • Oct 2016
            • 2

            #50
            To clarify, my router (a Netgear Nighthawk) had picked channel 12 on 'auto' setting.
            I had to manually change it to 11 to get the Evohome to connect.

            Comment

            • roydonaldson
              Automated Home Guru
              • Jan 2013
              • 205

              #51
              Interestingly enough i just had this exact same problem. I upgraded the firmware on my wireless access point and all of a sudden my EvoHome controller isn't connected anymore and can't even see my broadcast SSID. Eventually after looking at the AP, I see it has now autoselected channel 13 to run on on the 2.4Ghz band. I change it from auto to manual and pick channel 1 and the EvoHome controller rescans and finds the network first time. Hmmmm.

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