2013 MBA with 802.11ac won't choose 5GHz even when faster

This is wrong, in regards to 802.11ac. None of the improvements in 802.11ac are possible on the 2.4GHz band, hence why none of those improvements where brought there. Because of this, typically, even when the signal is weak, the 5GHz band will perform far better than 2.4GHz band. Plus, in many urban areas, the level of interference typically encountered on the 2.4GHz band can destroy much of the range advantage, and certainly hurts performance even further.

The solution I'm using currently, is to change the 5GHz network's SSID, via AirPort Utility, which allows me to stay connected to the 5GHz band permanently, on devices which support 802.11ac. I just settle for 2.4GHz on devices which don't. Has been working well thus far, except that Macs seem to be configured to try to connect to the 2.4GHz SSID when the 5GHz one isn't found, and for some reason the AirPort Extreme keeps broadcasting the 2.4GHz SSID for longer, which then adds the SSID to the list of networks, and causes problems. Luckily, this only happens when I have to restart it, which is almost never.

Definitely not a perfect solution, but it works.

5ghz is far less about proximity than it is about obstacles. Your Air is selecting the connection with the highest gain.

For example when i walk outside with my Air, its on 5ghz until i get in the car and shut the door upon which 2.4ghz is chosen.

high frequency is better, ONLY in line of sight instances where obstacles are nill or low.

(training from ham radio tinkering for 20 years) 😊

One option is to rename SSID and then manually select network.

I agree, but in reality the 5ghz band only gives maximum throughput when you are in the small room, no obstructions, and are within 12 feet. After that you will see better performance, (throughput) on the 2.4 ghz band

I have set up separate networks and my MacBook will select the 5 ghz network automatically - when I walk out of site the Airport Extreme I manually switch over to the 2.4 GHz band.

I actually install large wireless networks professionally, so maybe I can help clear up a few misconceptions.

To the original poster, there really isn't a way at this point to force the MBA to select the 5.0GHz network, but this really isn't a "bug" of the MBA. It's really a missing feature from the AirPort.

Your assumptions on how the client device works are correct. They select the band based on the signal strength (basically Signal to Noise Ratio [SNR]). This is actually a function of the NIC itself and is based in the hardware. Since the vast majority of client NIC cards are manufactured by a couple of companies, it will probably take them a while to change the operation, and for marketing reasons, I don't know if they want to at this point.

The vast majority of people that I encounter every day don't understand that there's more to wireless performance than signal strength. They look at the corner of their device and say, "I have 4 bars, look at how great my network is. Yeah, it's a little slow, but that's just how wireless is". Companies that sell consumer wireless access points are able to say "Cover your house with a single device". I really think that the lack of consumer awareness is what causes trouble for those of us (like the original poster) that understand that there's more to it than that. Even OS-X falls into this marketing bubble. Why do I have to hold down Alt and click on the wireless icon to actually see performance data? In my opinion, the icon should be the Transmit Rate as a number and I hold Alt to see the RSSI when I need to troubleshoot, but that would scare most people. For these marketing reasons, I don't think that you will find client devices selecting 5.0GHz by default until 802.11ac really gains in popularity.

The other option, which wouldn't require a tremendous amount of work on Apple's part is a feature that many enterprise wireless manufacturers refer to as "Band Steering". Basically, the AP (AirPort Base Station) will ask the client for its capabilities. Once it knows that the client is 5GHz capable, it pushes the client over to that frequency and there isn't anything that the client can do about it. If I knew how, I would be requesting that feature as an advanced option of the AirPort product line. That way, those of us that really care about wireless performance are able to get it without having to hack through and broadcast a 2.4GHz network that will basically be unusable in the coming years since the new wireless standard is 5.0GHz only.

jaysoares wrote:

If I knew how, I would be requesting that feature as an advanced option of the AirPort product line.

This is how:

AirPort Express: http://www.apple.com/feedback/airportexpress.html

AirPort Extreme: http://www.apple.com/feedback/airportextreme.html

Time Capsule: http://www.apple.com/feedback/timecapsule.html

Sorry to necro this thread but just touching base that this is indeed an issue on the 2015 MacBook Pro Retina as well.

- If I configure my Time Capsule (802.11ac) to provide 802.11a/n/ac at 5ghz and 802.11b/g/n at 2.4ghz using the same SSD I get pretty good AC performance within a room or so of my base station - 800+ Mbps Tx rates and throughput the maxes out my internet connection (300/20 DOCSIS). Sounds good. Latency is good and throughput and jitter is good.

- Within sight (or in the next room), my MacBook Pro will always select the 2.4ghz network unless you turn off the WiFi and then turn it back on again - at which point it reconnects to the 802.11ac network with the above stats (800Mbps+ TX rate). Annoying, but so be it.

- I have a home office which is actually built onto my house - which is to say, one of the walls in my office is the brick outside wall of the house (or it was an outside wall before the office was built and added on). In this room, my MacBook always connects to my Time Capsule at 2.4ghz and I get about 120mbps Tx rate with effective throughput closer to 40Mbps. Worse, latency is higher and the connection has severe jitter. Throughput can stall out completely at times and pings range from 3ms to 500ms+ just pinging the Time Machine itself. Most of the time everything is fine but, as you'd expect, it always seem that i'll be on a Skype call right when the connection decides to stall.

- I've recently done some experimenting in which I changed the name of the 5ghz network on the 802.11a/n/ac network. If I delete the 2.4ghz network configuration from my MacBook Pro and connect ONLY to the 5ghz network, I get a reported Tx rate of about 45Mbps. Seems worse... but, actual throughput is closer to 200Mbps and latency and jitter are excellent.

So, 5.8ghz 802.11ac is delivering far better throughput in all of my house than 2.4ghz is. Now, I live in Toronto and in a very populated area (I see about 30+ 2.4ghz networks in my house at any given time) so that is probably to be expected, but the problem is that, as I describe above, the MacBook simply refuses to the use 5.8ghz network if left to it's own decision making and, even when forced, steadfastly contends that the Tx rate is lower despite real world throughput showing this not to be case.

Basically my conclusion is that some part of the Apple stack (be it the Time Capsule software or hardware or the MacBook pro software or hardware) isn't capable of selecting anywhere near the optimal frequency band, and in my case, often makes such a poor decision as to make the connection problematic.