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TallBearNC Author

Level 1

34 points

iOS 4.3 breaks Wireless N (802.11n) in 2.4 and 5 GHz bands on iPad, iphone4

It's not just in the 5ghz band as I first thought.

I put 4.3 back on things and did more tests..

4.3 prevents ANY iDevice , including the ATV2 from using 802.11n in any band.

Many ppl don't see this because their routers are in mixed mode. So for 5ghz ppl , the devices drop to 802.11a, and for 2.4ghz ppl, the devices drop to G.

I hate mixed mode on routers because it degrades performance(so I don't use it). So my 5ghz band is N only and my 2.4 is G only. So I noticed this right away. But once I set my 2.4ghz to n only mode , no idevice running 4.3 could connect to any band. nothing would touch it

This also is not a 40mhz vs 20 issue as my 5ghz was forced to 40 and the iPad and ATV used it just fine under 4.2.1, and i tried 20mhz N only on both bansd and still nothing would connect.

I'm a computer engineer and programmer so I troubleshooted every possible cause with this affecting all idevices, and what I see on the forums this is a HUGE screw up in the release of iOS 4.3

I'm just shocked there are NO press releases. 54Mbit is not enough to stream HD movies to an iPad. The iPad does not buffer to storage like the ATV2, it buffers to ram. So on a G/A network, HD video streams to my iPad then stops every 1-2 mins

However, I was able to downgrade everything to 4.2.1 again because apple is still signing it

I started a new thread , this one, with a better title so search engines, etc can find this info easier

Message was edited by: TallBearNC

Dell XPS 720, Windows 7

Posted on Mar 12, 2011 8:33 AM

60 replies

thanxal

Level 1

37 points

Mar 13, 2011 5:29 AM in response to Fubar_UK

Anyone know how to do this on an Apple Airport Extreme?

Mar 13, 2011 2:28 PM in response to TallBearNC

setting the WME option was no help for me

Mar 13, 2011 2:48 PM in response to Fubar_UK

wmm is mandatory for 802.11n. why don't tech support people know? because they are monkeys sitting in a call center with little to no knowledge of anything more than suggesting rebooting or reinstalling software.

iFrodo

Level 1

45 points

Mar 14, 2011 12:40 AM in response to TallBearNC

Great for you, but my router doesn't have any WMM or WME option, so I simply can't fix this issue myself.

That is not normal that you can't use 802.11n without WMM, Apple should fix that ASAP on iOS itself.

tgibbs

Level 1

70 points

Mar 14, 2011 7:18 AM in response to iFrodo

iFrodo wrote:
Great for you, but my router doesn't have any WMM or WME option, so I simply can't fix this issue myself.

That is not normal that you can't use 802.11n without WMM, Apple should fix that ASAP on iOS itself.

As others have pointed out, WMM is required by the 802.11n spec, and 802.11n will not function properly without it. So if your router does not support it, it is a router problem; a fix from Apple is unlikely. If you can't get an update from your router manufacturer, you might want to check whether your router will support the open source router firmware that is available on the net

Mar 14, 2011 12:41 PM in response to TallBearNC

I have a similar problem. There are two iPhone 4s on my Netgear WND3700 router. The problem started when I upgraded one of the phones to 4.3.

My phone would keep dropping wireless connection and would sometimes could not log on to my network.

I have a temporary fix - I set the router option form upto to 300 mbs to 130. I assume this makes not run in N mode.

Apple needs to fix this problem.

BG-Pete

Level 1

0 points

Mar 14, 2011 1:07 PM in response to TallBearNC

I have not yet upgraded to 4.3 and quite frankly, am a little afraid to. My wife's iPad2 is on order and I want to make sure hers works properly or I will never hear the end of it...lol. I have a Linksys E3000 router. I looked everywhere. Does anyone know where in the router configuration I need to go in order to enable WMM. Thanks for the help.

Mar 14, 2011 4:10 PM in response to BG-Pete

it's right in the user guide on the linksys site: http://homesupport.cisco.com/en-us/wireless/linksys/E3000. it's enabled by default. enabled should be the default on any 802.11n certified access point.

Naulak

Level 1

0 points

Mar 15, 2011 9:14 PM in response to TallBearNC

really hate this ... my ipod touch 4g couldnt connect to my ad-hoc post the ios 4.3 installation .... could you please help me on how you downgraded the ios? ive been to the service center and called the customer care ... they just told me there is no way of downgrading after the upgrade .. thanks !

JKtheMac

Level 1

0 points

Mar 18, 2011 4:24 AM in response to BG-Pete

After a bit of settings wrangling I have finally managed to get a consistent connection on my Linksys E3000, as mentioned WMM was part of the problem, but turning it on made my connection intermittently drop out. CTS Protection Mode has proved to be the cause of this, as setting this to disabled has meant that I only very occasionally see a split-second drop of network, and streaming video has not been a problem since.

BG-Pete: WMM can be found under Applications and Gaming / QoS
This setting is indeed on by default but so many people across the Internet seem to think that WMM is a problem with multiple equipment, you may have turned it off.
Also, CTS Protection Mode is found in Wireless / Advanced Wireless Settings and can be individually configured for each frequency.

BG-Pete

Level 1

0 points

Mar 18, 2011 7:05 AM in response to JKtheMac

Thanks JK. I found those settings and WMM was enabled and CTS is set to auto. Still have not upgraded to 4.3 since I am waiting for my iPad2 to arrive and I have my iPad "classic" sold. Hopefully, thing will go flawlessly...yeah right.

JKtheMac

Level 1

0 points

Mar 18, 2011 6:11 PM in response to BG-Pete

Just to clarify I had to switch CTS from auto to OFF in order to get a solid connection. However CTS is designed for heavy traffic from multiple devices so it shouldn't be an issue in most homes. However, CTS issues may explain the problems some have had in public wifi locations.

My ideal solution (based on my devices and local noise) was to have different SSIDs for 5GHz and 2.4GHz and set 5GHz to N only and 40MHz width. I then use 5GHz purely for my iPad and everything else on 2.4GHz (mixed mode).

mike.mn

Level 1

0 points

Mar 18, 2011 6:51 PM in response to TallBearNC

This fixed my problem too. I just downloaded OS 4.3, and my home WIFI would no longer connect. I changed my router settings to enable WMM, and problem solved. Thanks for the tip. Curses to Apple for changing this without notifying us. Seems more like something MS would do!

tgibbs

Level 1

70 points

Mar 19, 2011 9:46 PM in response to mike.mn

Some people seem to have some remarkably unrealistic ideas about what Apple can be expected to test for before releasing a new OS update. Is it really reasonable to expect that Apple should have checked for whether the update will work properly under 802.11n if the user has mistakenly disabled a service that is required for the 802.11n specification? There are a lot of routers, and a lot of possible ways to misconfigure one. Apple is not going to be able to check the consequences of every possible user error.

TallBearNC Author

Level 1

34 points

Mar 19, 2011 10:44 PM in response to tgibbs

Completely reasonable. Any devices like that, that relies on wiresless should always be tested on at least the major brand routers and key models. That's not too much to ask at all. If they can't at least do that, they have no business making wireless devices.

This isn't some random bug, its a feature (well requirement to use full 802.11n speeds) that apple decided to "require" users to use without any heads up or notication. Not to mention idevices have inherent issues with WMM that apple has never bother to even fix. So why they chose to suddenly be fully 802.11n compliant, and enforce it, and not let ppl know is beyond me.

Before iOS 4.3, if u were in N only mode w/o WMM, the router would stay in N mode but limit it to 54Mbit, and ur idevices would connect. Once 4.3 came, devices just up and refused to connect with no reason why, and apple kept silent and acted like they had no idea what was going on. Technical users, like me, figured out the problem and posted to the forums and let apple support know

Again, that's not our jobs, we are not alpha and beta testers. I know now that iOS is about as buggy as MS windows with their updates, etc, and I won't put any new iOS on any devices till I read the forums and check the Internet for major issues. Often downgrading is not possible as apple stops signing the old build within 24-48hrs. Personally, I think they should keep signing the prev version for 30days so ppl can rollback that have major problems

So far the most stable 802.11n config I can come up with under iOS 4.3 is WMM, no acknowledgement disabled. If NA is enabled the iPad and atv2 constantly drop off the network at random times on many cisco, linksys, and net gear routers. When Apple release 4.3 it was their duty to let ppl know that should configure their routers in such a way that best

Lastly, I used to work for Apple, and many other major software and hardware companies over the past 20+ years. I know what's realistic or not, and how big companies deal with PR issues by either coming forth or playing dumb/silent.

iOS 4.3 breaks Wireless N (802.11n) in 2.4 and 5 GHz bands on iPad, iphone4