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why does a WiFi extender need to simultaneously broadcast on both 2.4 GHz and 5 GHz frequencies?

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Last Modified: 2020-02-23
Hello and Good Morning Everyone,

         Recently, I ordered and set up a WiFi extender provided by AT&T.  I did notice that both, the 2.4 GHz and 5 GHz lights are a steady green which is the way it is supposed to be.  Just out of technical curiosity, I am wondering why the WiFi extender needs to simultaneously broadcast on both frequencies as opposed to just one.  

          Any shared views or thoughts regarding this question will be appreciated.

          Thank you

          George
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Technology Director
Commented:
I think it is dependent on the main AP. If both frequencies are active, then the extender will extend both.
Try turning 2.4 Ghz off on the main AP and see if the extender keeps 2.4 Ghz or not.
Dr. KlahnPrincipal Software Engineer
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Commented:
Go into setup on the extender.  It is usually possible to disable one or both bands.
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Commented:
It "needs" to broadcast on both if it is expected to extend both.  They are independent of each other.  As mentioned above, you may be able to turn off one or the other.
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Top Expert 2014
Commented:
It really depends on the extender and your setup.

Some extenders will use one frequency (e.g. a channel in the 2.4 GHz range) for the back channel (i.e. the link between the base station and the extender) while using the other frequency (e.g. a channel in the 5 GHz range) for communication to the client devices.

If the extender is not capable of doing that then it functions as a repeater - listening for the signals from the base station then repeating them to the clients (and the reverse).  Basically a wireless device (AP, client, whatever) can't send and receive (talk and listen) at the same time on a single frequency.  Because of this, when using a repeater the bandwidth between the base station and the client effectively gets cut in half.

If the extender can use a separate frequency for the back channel it can still send on one frequency while receiving on another, so the bandwidth isn't impacted.  Outside of the using a back channel, the extender could also just be acting as a repeater for both frequencies.

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Commented:
Hello and Good Morning Everyone,

           Thank you everyone for breaking this down to a level that makes sense to me.  According to the setup instructions which came with the WiFi extender, both, the 2.4 GHz and 5 GHz frequencies need to be broadcasted at the same time.  From what I gathered from an AT&T representative, the WiFi extender will not have its own or independent IP address.  That said, I am not sure if it is possible to login to its setup seeing that it is merely taking all of the information being broadcasted from the AP and sending it to the client iPhone on the other side of the wall.  

            With respect to performance, which is most important, my friend on the other side of the wall is able to surf the internet, do online chatting, and check emails.  However, there is a buffering issue noticed whenever he tries to watch a video on YouTube or watch a movie online.  This is an issue that will need to be followed upon more.   Other than that, everything seems to be working okay.

             George