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I've a network that is powered by an Airport Extreme and extended by an Airport Express. My Airport Extreme broadcasts 5 GHz and 2.4 GHz channels separately.

2.4 GHz operates on channel 4 and 5 GHz operates on channel 44. The network is WPA2 protected. 'Router Mode' is off. 'Radio Mode' is 802.11 a/n - 802.11 b/g/n (Automatic). And my 'Country' is selected to United States.

Also everything, including my network gear and things that connect to it, is up-to-date. And I'm not on any other DNS.

Recently I made the Airport Express extend the 5 GHz channel instead of the 2.4 GHz one because of 5 GHz's better performance.

But now when I connect to my 5 GHz channel I get worse performance than my 2.4 GHz one.

Below are the screenshots of my tests on both of the channels. The faster one is the 2.4 GHz one. (by the way, I know it's a shame but unfortunately that's the situation in my country at the moment, hopefully there will be fiber soon)

performance on 2.4 GHz channel performance on 5 GHz channel

What exactly is causing this woeful performance on 5 GHz? What am I missing here?

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4 Answers

up vote 2 down vote accepted

The 5GHz is all hype. It can be faster, only if you're close to it. 2.4GHz is still superior in range and as you know, WiFi speed drops off the further away you get from your access point.

The only time I've found 5GHz useful is: When many other networks are interfering with mine. (in between two large apartment buildings with 12+ networks bouncing within the corridor, it's nice to switch off of the 2.4GHz)

Or, if I'm in the same room as the AP, I can get a strong signal. Then 5GHz is sometimes faster.
here's something interesting from wirecutter.com

No matter what they are called or technology they use, repeaters start out with a minimum 50% throughput loss. The reason is that a repeater must receive, then retransmit each packet using the same radio on the same channel and with the same SSID. If the repeater is very efficient, then your loss will be close to 50%. But if it’s not, throughput loss can be higher.”

Thanks to that 50% loss in bandwidth right off the top, just about all wireless extenders suck.

http://thewirecutter.com/reviews/best-wi-fi-extender/

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Nice insight. Long ago before this problem I was wondering why I was getting 75% output just near my Airport Express. –  Can Sürmeli May 23 '13 at 11:50
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Before making any attempt to use any wireless channel, you should first analyze your wireless environnment and its pollution level.

For this kind of analysis, I advise you to use iStumbler which is a pretty good tool to analyze wireless environnment.

Once you have sorted all your neighbor networks along their signal strength, you'll be able to choose a free channel. This may as well be on channels from 802.11b than the ones coming from the 802.11a.

If you find equally free channels on 802.11a and 802.11b, here is a trick to help you choose between channels of each sort. If you are rather far (between 15m and 25m) from your AirPort Express I advise you to choose the 802.11b. If you are rather near (below 15 m) of your AirPort Express, you should choose the 802.11a.

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I will try iStumbler but I tried Apple's own network analyser in Mountain Lion before. And I choose those channels from that report. –  Can Sürmeli May 23 '13 at 11:56
    
→ Can: please report your personnal comparaison between these 2 tools. I'm highly interested. –  daniel Azuelos May 23 '13 at 12:03
    
Here you go: cl.ly/image/330D413i3X3d & cl.ly/image/1W0P392l0v3D –  Can Sürmeli May 23 '13 at 20:40
    
→ Can: thank you. On both tools, you should sort your networks along the Signal column. From the displayed graphic in the upper left corner of iStumbler, this channel 44 can't be used in this point of measurement (regular total dropouts). Could you replace in your original question the graphics by the ones from iStumbler with the channel 44 alone, and then the channel 4 alone, from the same measurement point and for a duration larger than 5 minutes (so as to fill the upper left graphic)? –  daniel Azuelos May 24 '13 at 14:52
    
Sorry for the late response. My plate was full with finals. In the mean time, I made a change to my network that I cancelled extending the 5 GHz channel because of the dropouts. I'm gonna change the 5GHz's channel and then upload some more detailed screenshots of the analyses' that I will make from different points. –  Can Sürmeli May 30 '13 at 13:46
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Try rolling back the AirPort Extreme firmware. When I updated to the latest (7.6.4 IIRC) on my Airport Extreme I had much worse wireless performance on both bands but 5ghz was deteriorated to the point that it ceased to work in the same locations that it worked fine pre-firmware update. You may have to install Airport Utility 5.6 which is the last version of the old airport utility. They can both exist on the same Mountain Lion Mac. I rolled back to 7.6.2 and 7.6.1 (7.6.3 is for the new Apple TV style airport express only AFAIK) and didn't get any relief until rolling back to 7.6

All the Best

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(I've got 7.6.3 on two AirPort Extreme:s.) –  Qerub Sep 5 '13 at 16:01
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I have the same setup as you (5GHz Airport Extreme on top of 2.4GHz router - the wifi of this one can be on or off), except that something I did changes completely this scenario. The 2 base stations are close, so there is no reason I should not set the Airport as a repeater using an Ethernet cable and not as and extensor.

The problem, as everyone called out, is that the repeater is another point on your network and this time makes a lot of difference because it's another wifi transmission.

So, if you are going to extend the wifi range or want to go with 5GHz, from another router, make sure you do the hard work of wiring, because it will be only once, but you will benefit every time you use it and a lot. Remember, wifi is already kinda lossy transmission.

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