If you are confused about how to setup for 20 Mhz or 40 Mhz bandwidth for your router, you have come to the right guide here. We will go over some simple rules to help you decide the best bandwidth to use for your wireless network.

How to Choose 20 or 40 Mhz?

The answer is it depends on the devices that you have in your house. The answer lies closely with the type of radio broadcasting that you have chosen. The strategy to figure out the best radio broadcast can be found with out 2.4 ghz vs 5 ghz wireless guide.

When You Should Use 20 Mhz for Channel Width?
If you use 2.4 Ghz broadcasting radio, you should use 20 Mhz for the channel width. The simple reason is that 20 Mhz is really a supportive measure for your older devices. Using 20 Mhz on a 5 Ghz radio setting defeats the purpose of actually using 5 Ghz radio setting.

The only exception is that you somehow has a devices that support 5 Ghz broadcasting while only accepting a 20 Mhz bandwidth, however that is fairly uncommon. But if that does happen, see if your router supports duo bandwidth for both 20 Mhz and 40 Mhz.

When You Should Use 40 Mhz for Channel Width?
If you use 5 Ghz broadcasting radio, the chances are that your network is only consisted of the latest devices that support 802.11n. This is when you should use the 40 Mhz bandwidth.

When You Should Use Combination of 20 / 40 Mhz Combination.
Only use 20 Mhz / 40 Mhz combination if one of your devices require it. If not, just set it to 40 Mhz.

How to Control Channel

For 20 Mhz broadcasting with 2.4 Ghz
The best channel band to use are 1, 6, 11

For 40 Mhz broadcasting with 2.4 Ghz
The best channel band to use are 3, 11

For 20 Mhz broadcasting with 5 Ghz
You should use 40 Mhz instead of 20 Mhz, or use combination if your device needs it and the router supports it.

For 40 Mhz broadcasting with 2.4 Ghz
Any channel with the least amount of interference will do. The chances are you are free to use any channels. Consider using the auto function so that when your router can auto adjust for the best channel to use.


Setting Up 20 Mhz or 40 Mhz Bandwidth — 31 Comments

  1. very nice post in all yuor webblog. i need help i use as a access point bullet m2 hp in 1.5 km outdoor with omni anteena 15dbi when my user connect with my access point single strength is full but speed who below the single decrease (65mbps,36,26,13, at last 1.0mbps .when 1.0 slow browsing and cut off skype and any other talking messenger talk . How to solve this isse.

  2. “Using 20 Mhz on a 5 Ghz radio setting defeats the purpose of actually using 5 Ghz radio setting.”

    Clearly false information. What if the user’s entire purpose of using the 5G radio band is network congestion on 2.4, rendering it unusable?

    • 2.4 ghz congestion won’t affect 5 ghz, if 5 ghz is congested(not likely) than using 20 mhz on it might help though.

    • You’re wrong. A 5 Ghz radio broadcast are made for higher frequencies. Which gives more bandwidth. Using 20 Mhz frequency with that high of radio broadcast will only cause the signal to become redundant. Causing it to have unstable connection. Think of it like a jet only traveling at 100mph. Jets are designed to go fast! Not slow…thus trying to fly (not hover) a jet that slow is little to impossible.

        • Regardless of OP’s ability to use proper grammar & articulate an accurate analogy if his comment was in fact subjective I dont see how it could remain an analogy when analogy is by definition a “literally truthful” comparison, which we are clearly unable to use as a label when referring to an analogy that is as you put it, subjective. I guess what I’m trying to say is since our friend Oliver, with his poor grammar and unimaginative analogies (which I believe insofar as analogies go is exactly what one hopes for) obviously has a tenuous grasp at best in the operating procedures behind internet gateways hand, we can hardly expect his; although concise and most definitely NOT subjective-we can all agree planes cannot fly at 100mph or 160kph for our European friends….wish I could finish this thought but real life is calling

          • I could agree with you but there’s no point in both of us being wrong. These Planes you speak of not only fly at cruising speeds of less than 100mph, they may at times fly backward; which I believe is under 100mph. Relative to the mass that surrounds da’plane is more significant than simply distance over time. True and Indicated air speeds are used to determine lift, flap adjustments, roll, stall etc–.–measured in knots. My apologies, please. I cannot match your wit, kinda boring I know. Nevertheless, my awareness of statistical thermodynamics and creative ability prevents me from falling into the frightening realm of the logical fallacy of which you seem to thrive. Kudos.

  3. What about the sideband control channel? How does it fit into this? How does it work? Should it be upper or lower? If they call it Control Channel, should it be upper if you select a low channel like 3?

  4. I was experimenting with 20Mhz or 20/40MHz (these are the only two settings on my router) on 2,4GHz and I noticed that if I set the 2,4GHz to use 20/40Mhz my wireless (not WiFi) mouse started to act funny, not to say it became unusable. As soon as I set it back to 20Mhz, my wireless mouse worked perfectly.

    Just a FYI if anybody ever has a similar issue.

    • This is very interesting!

      I might have similar issues but with different frequencies. When I set 20Mhz on 2.4Ghz router, my wireless mouse acts funny as well. Almost as if my battery was low.

  5. For 40 Mhz broadcasting with 2.4 Ghz

    “Any channel with the least amount of interference will do. The chances are you are free to use any channels. Consider using the auto function so that when your router can auto adjust for the best channel to use.”

    I would be careful with this one. Especially the quote doesn’t give good explanation for proper using this setting for a reason. I would do multiple speedtests after using this setting on my modem. While doing the test, I would get 4mbps higher than my max mbps for what I paid for (28mbps than 24mbps “paid for”). It was great! Other times, would get no more than 3mbps :-O

    Really depends on what devices are around your house & your neighbors internet settings.

    • Oliver, when you are paying for internet you can expect to lose 20% of your speed before complaining. Please don’t be concerned with 3 or 4 Mbps for any reason. You could have looked at you router wrong and lost more speed “that you’re paying for”. I would hate to be tech support for your ISP.

      • There’s a big difference in 24 and 3. Read before you’re rude to someone. I’d hate to ask you for computer help..

      • for real, Roy’s immediate transparency shows the mentality and subsequent behavior that makes “the helpless” give up before even looking for help, and makes the helpful AND adept fucking cringe to bear witness to such worthless “insight”.

        Worse still, is knowing the principal actually gets paid, somehow, to do so! (although, you’d never know from the quality of advice, but loathsomely it’s because their every post includes a pontification touting his or her “credentials”).

  6. I have a weird problem with my wifi router at home. Actually i am living in europe and i am using vodafone ADSL Wlan easybox 804 router. Since last week, some of devices such as smartphones and my laptop don’t work with the wifi even the wifi is always ON. Some of my devices can still work. For example; i have two smartphones, galaxy S4 and galaxy A3. With my galaxy S4, wifi is working, but with galaxy A3, there is no wifi SSID at all. When i want to enter it manually, it doesn’t work as well. Some of devices can search for the SSID, but some of them are not able to search it. I reseted my router and reconfigured it, but it doesn’t work. I also reseted my phone, the proble still exists. I searched on the Internet for any solution, but no clue!

  7. Any channel with least interference will do? Not so, you should only really use non-overlapping channels 1, 6 , 11 on 2.4GHz

  8. Download a Wifi Analyser to your phone like (Keuwlsoft).
    I have two Wifi routers connected with power line Ethernet. Running on same SSID.
    This means I need to force them to different channels. Channel 1 is at 2412MHz and channel 11 is at 2462MHz. (This is the middle value in simple..)
    The width of the channel is determining how much data can pass through / s.
    If you select 20MHz width it is + -(width/2) to the channel value. You should avoid the overlaps.
    Overlap cause data loss and faulty communication. The neighbor also have Wifi so consider it as challenging networks the same way.
    Decide what is important reliability or transfer speed. There are just situations where you can’t reach the speed you need anyway. (Overcrowded channels 50 Wifi router etc.. The phone app can show the hidden SSID wifis too with no name.)
    The Wifi signal in many cases cannot go through objects. Consider opening/closing doors can change a lot in signal strength as reflections and dead zones are very likely.
    Using the 5GHz band will lower the signal penetration and distance for same strength but offer now a days mostly free channels really. Also the higher frequency carries more information / s.
    The point is not to just blindly raise the width. Look for the gain too on your signal. It should be around -40 -50d to be reliable. (But it depends on many things. See the com protocol level if you have a lot lost packets. And what is a lot etc..) It never ends if you go deeper.

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