Solving Airport’s Mystery Dropouts

Ever since Christmas of 2007, I’ve had a problem. Sudden, seemingly random Airport signal dropouts. These frustrating gaps can last anywhere from a few seconds to minutes or even hours. When this happens, the internet connection in our second story bonus room is lost completely. Sometimes it comes back on its own but lately we’ve had to turn Airport off and then on again to re-acquire the wi-fi signal. The problem has been so bad that I’ve even considered calling an electrician to hard wire the bonus room for CAT-5 cable. A costly and extreme solution to be sure. After two solid months of vexing investigation, I think I’ve solved the mystery. If you’ve been experiencing sudden wi-fi dropouts on your airport enabled Mac, read on.

The Usual Suspects

I’ve been reading about Leopard wi-fi problems for weeks but since our Macbook Pro is still running Tiger, these reports didn’t make sense. Perhaps it was one of the three Airport base stations we have in our home. The Airport Extreme in our home office acts as the router, and there is a second Extreme in the upstairs bonus room itself. When we first moved into the house four years ago, I set up an Airport network with an original UFO base station and an Airport Express in the hallway of the second floor. This served well for years, and when the new Airport Extremes were released, we upgraded but left the Express to boost signal.

All seemed fine until around Christmas when the dropouts started. At first I thought it was a hardware failure and tried swapping the Extremes, changing their location in our home, altering the configuration of the network from b/g compatible to just g, then to n. I tried closing the network, removing the Express completely, etc, etc. Despite all of this, the network dropouts persisted.

Next I tried removing the other Wi-Fi enabled devices in our home. Through a process of elimination I removed our Nintendo Wii, my wi-fi enabled iPhone and even my TiVO from the Airport network. I had suspected the TiVO for a long time since the dropouts seemed to come at set 5 or 6 hour intervals (when the TiVO was downloading program info?) and was disheartened to discover that after dissconnecting the TiVO for a full 2 days, drop outs were still the rule and not the exception.

A Break In the Case

The clue to the solution came when I made the connection between when the problems started and the time of year. I said earlier that the dropouts began shortly after Christmas of 2007, just when other families in the neighborhood would be getting wireless routers and hooking them up. Further clues were provided by my friend Craig Hockenberry that told me he has had similar problems due to interference from his neighbors. From Craig’s home, some 12-18 wireless networks are available. Being at the end of a dead-end street, I always assumed we were pretty isolated from interference from other networks. When we first moved in, my Airport network was alone in the neighborhood. But sure enough, a quick check with AP Grapher this week revealed between 6-8 other wi-fi networks. After a walk around the development, and chatting with neighbors, I was able to create a rough map of the wireless networks that surround our home.

Advances in 802.11 technology have dramatically increased the strength and range of home wi-fi networks. Unfortunately this also increases the potential for interference from one source to the next. You can see in the map to the right that although the house in pink is hundreds of feet away from mine, I still get a 42% signal from their wi-fi router. Craig turned me onto a few articles that talk about potential interference from sources like cordless 2.4 GHz phones, microwaves and especially other 802.11 devices. Suspecting one of these was the culprit, I watched AP Grapher like a hawk and noticed that our Airport channel would sometimes overlap those of our neighbors. When this happened, sure enough, a dropout occurred. In Mac OS X, I have Airport set to select channels automatically, and this turned out to be the root of the problem.

Book ‘em Dano!

When Airport is set to automatic, it quickly “scans” across the entire channel range and selects the one with the least interference to use. At the time of the scan, channel 11 may be relatively clear and so all is well. If however, a competing wi-fi network on the same channel turns on, or increases signal strength due to atmospheric conditions, that channel becomes cluttered with radio noise. The protocol for 802.11 is designed in such a way that when this happens, base stations can hold off broadcasting until the interfering signal goes completely away, which could be minutes, hours, or even days. This also accounts for the apparent randomness of the original problem.

Thanks to AP Grapher/Scanner, I can easily see the channels that all my neighbors are using for their networks. Since most wireless routers are set to channel 6 out of the box, avoiding this channel as well as two channels to either side is best. I’ve now set our Airport network to broadcast on channel 9 and I’m very pleased to report that so far, the dropouts that have plagued us low these many weeks, have ended. If you are able to manually set your wireless network channel to something that avoids the channels of those around you, this should do the trick. I foresee a time in the very near future however when the 11 channels currently used by wi-fi in the United States just won’t be enough. Hopefully, refinements in 802.11 technology (or something completely new) will stay one step ahead of the problem and keep us all up and running. Case closed baby!

Comments

  1. Brian says:

    I was experiencing similar Airport unpleasantness. But no more! Gracias!

  2. Tom says:

    At Gedeon’s request, I’m recounting my experiences with this issue. I apologize for the long narrative, but it helps me remember what happened.

    I literally read this post two days ago right after Gedeon published it. It made me stop and wonder about all those times my Linksys WRT54G would drop connections and none of my macs would be able to even see the router for 20 minutes at a time. It also made me wonder if I too hastily ditched it favor of an Apple Extreme Base Station N (AEBS). I reassured myself that the WRT54G was notoriously buggy and my switch was well-founded.

    Until last night. I sat down at my iMac to read emails and to appease my crack-like addiction to RSS feeds and noticed my connection was uncharacteristically slow. Thinking it was a fluke, I refreshed a couple pages and subsequently got connection errors. Below freezing temperatures can affect underground cabling, so I shrugged it off as a byproduct of the weather or a problem with the cable company. I hadn’t had any of the Leopard-related Airport issues previous to this, so there was no reason to think it was OS X. It was time to eat dinner, anyway.

    About and hour later, I pulled out ye ol’ couchputer (macbook) so I could update my site and watch LOST at the same time. I opened Coda, did my thing, and voil—”Hey, waitaminute, wtf. No FTP connection. But, but, BUT! I had just logged in to MovableType and my connection was fine!” And so went the cycle of intermittent connections and drops over the course of the next hour of watching John Locke be a jerk and trying to troubleshoot. Now I knew it wasn’t just the iMac, and my cable TV was just fine, so…

    I noticed at certain points that Little Snitch was showing no inbound or outbound packets, and then its menubar monitor would go nuts out of the blue. Then dead again. In my System Prefs, I was seeing an IP beginning with 164 instead of the Apple default of 10, despite the fact my network was chosen (to be clear, I do not leave anything with default names, not even my mac hard drives, so there was no mixup there). I would turn Airport off, back on, connect to my network, have the right IP, and then *BOOM*, and the connection would drop with a different IP showing again. Scary.

    I opened my Airport Utility and looked at the connected devices. My network is encrypted, and the right MAC addresses were showing up, so there was no reason to think the AEBS had been compromised. I rebooted the AEBS to be safe. Hopping back on the network, about 1 minute into surfing, Twitter & Adium went dead, as did Entourage’s dowloading a gazillion work emails. Damn.

    I heard Gedeon’s word’s start ringing in my ears, “If you switch it, you will surf”. OK, not really; I don’t even know what he sounds like. But it immediately dawned on me that the post-Christmas, Gremlin-like explosion of wifi networks in this apartment complex was the issue. And sure enough, like Ged wrote, my router was sitting on channel 7 when I went looking (according to Gedeon’s post auto-selecting deviates from channel 6 plus or minus 1).

    WIthin a few seconds I had the router set to channel 10 and within another minute the AEBS had rebooted and I have had solid connections ever since. In fact, I noticed that my VPN connection (which is usually doggedly slow) and my other connections are much faster overall. I don’t know how that works, but I don’t care anymore. Gedeon is made of magic in my book. As if he wasn’t before. Thanks for a simple fix!

  3. Fazal Majid says:

    An even better solution: upgrade to an Airport Extreme (or a Time Capsule) and set it to use the 5GHz band. You won’t have any interference since most routers are set up for 2.4GHz by default, even the pre-n ones, and in any case the range and penetration of 5GHz signals is less than that of 2.4GHz and thus the likelihood of interference is minimized even in the unlikely case one of your neighbors has a 802.11n 5GHz capable router.

  4. Shane says:

    Great info. Just be aware that the 802.11 b/g standard supports only three non-overlapping “center” channels – 1, 6 and 11.

    If you have your AP set to anything other than these you will still get interference from it’s closest neighbor channel, ie:

    10 – high interference from 11
    9 – medium-high interference from 11
    8 – medium interference from 6 and 11

    etc.

    This is because each center channel uses 23MHz of bandwidth (1Mhz guard, 11Mhz below and 11MHz above channel), so the spacing between these is required to allow the most amount of bandwidth for wireless data transmission.

    So in short – use 1, 6 or 11 as your channel and you’ll get best performance.

    Note: This does not apply to 802.11a or 802.11n (5.4GHz mode) that have a wider range of channels available to them.

    Regards,
    Shane.

  5. This solution likely won’t work for me because the problem isn’t the same: my computer drops the connection, not the AirPort. I don’t have interference (channel 1) and I don’t have to power cycle the AirPort.

    My Mac, since 10.5.2, drops the connection (93% signal strength – the base station is 10 feet away) on its own. I have to re-connect it from the menu or wait about 15 minutes and it seems to reconnect itself (judging by email error logs).

    I wrote about my experiences here: http://nslog.com/2008/02/15/1052_and_airport_network_drops

  6. bikeham says:

    My Airport Extreme reboots everytime I go to http://www.trackstick.com, but not when I go to http://www.trackstick.com.au

    I haven’t a clue why.

  7. Jan says:

    I own an Airport Extreme set to 5GHz and I still suffer from a lot of dropouts on my MacPro with 10.5.2

  8. david says:

    i have a similar issue
    what are your thoughts?
    my roomie has a windows based setup.. i think its a linksys router

    whenever he logs on his hard wired connection..
    i lose signal on my macbook..
    then if i log off then back on network – i’m good

  9. Peter Baker says:

    I had the exact same problems with a brand new Airport Extreme in both 2.4ghz and 5ghz mode, with or without Airdisks, with or without other routers extending the network, etc. One simple thing has fixed it for me since changing it and I haven’t had a problem since:

    Downgrade the Airport Extreme firmware from 7.2.1 to 7.1.1.

    Zero problems since then.

  10. Ged says:

    Peter, would you mind posting a short procedure for how to go about downgrading the Airport’s firmware for those who want to give it a try? Thanks so much!

  11. Simon says:

    OH MY GOD!
    Thank you so much!!!

  12. Charles says:

    I’m going to try your solution later tonight (after my online class). Hope it works. I actually returned an Airport Extreme base station a few weeks ago for a new one because of this problem. I thought it might have something to do with interference — lately there’ve been two new wireless networks in my apartment building within range of my unit, making the total five including mine.

    However, I also have an Airport Express as a backup. When the old Extreme kept dropping out I switched back to the Express and an old Netgear wired router. Not as fast, but no dropouts at all. I also find that the Extreme drops out more the more data I’m pumping through it. (The model I returned would die after thirty seconds downloading Ubuntu torrents.)

  13. Peter Baker says:

    By the way, to downgrade your firmware, select “Upload Firmware…” from the Base Station menu, and there will be a drop down with a few older firmwares.

  14. GreenCountry says:

    @Shane:

    My experience re: your advice to use channels 1, 6, or 11 points me to the totally opposite direction. I don’t know about the technology behind why 1, 6, or 11 are more desirable than other channels, but when I have used one of those channels (by either allowing Airport to auto-select or by manually selecting them) my network speed has always been abysmal. When I’m on another channel (my favorite are 3 and 9 due to no other networks on them), my speeds are *much* better. Even if, as you say, there is bleed-over interference from channel 11 on 9 or from 1 on 3, it seems not being in direct competition with all the other networks on 1, 6, or 11 is still more desirable.

  15. Ged says:

    Shane, I’m not saying to always use 1, 6 or 11, I’m just saying you should use AP Grapher to find out what other channels are cluttered interference wise and select one (if possible) as far away from those as possible. Hope that helps to clarify.

  16. Ian says:

    Possible airport dropout fix?!: I too have having dropout/slowdown problems with my airport express. When pinging I was getting normal times with huge times every second or so. I had tried all the usual things like changing channels, and other airport prefs etc etc, but nothing seemed to solve the problem. Anyway, a few minutes ago I just noticed that in the console log I was getting an error every few seconds, saying ‘JavaScript says: powerString is screwed up’, after a search for this phrase in google I found out that it’s a jwire widget problem, deleted jwire and all seems fixed. When pinging I’m getting normal times. It may be coincidence and this may not solve problems for other people but if you’ve been having airport problems, check your console log and try deleting jwire. Hope this helps!!! Ian

  17. Alex says:

    Will someone post this 7.1.1 firmware for me to download? I have the gigabit version of the Airport and it only goes back to 7.2 firmware. I’ve been searching for the 7.1.1 firmware for months!! NeverEnuf81@mail.com (this is not my main email, but it can accept files)

  18. :HAn. says:

    Unfortunately, upgrading to a Time Capsule did nothing for me. I had an old UFO Extreme running g only. Constant drop outs. I thought the 802.11n would help if I changed frequency to 5GH, but its the same exact problem! It keeps the Airport at “automatic” but seems to stay on channel 36. No other transmitters are using channels anywhere near that (most 6 /1). This is INDEED A MYSTERY!!!!

  19. bubba says:

    Use 5GHz if at all possible.

    Otherwise use only channels 1,6,11. They are the only ones that do not grossly overlap each other. 3 overlaps 1 and 6. 9 overlaps 6 and 11. Also, if two networks are using the same channel, they may understand what they’re competing with and actually cooperate a little. If they’re on a different interfering channel, they will look like noise to each other and try to shout over each other.

    Sounds like apple needs to work on being a better citizen of a crowded wireless world.

  20. Martin Bradford says:

    At last a voice in the wilderness – I’ve been trying to tell people this on the Mac support forums for ages, but nobody wants to hear it! But I do think that the problem is a little more complex than simple wifi interference and Apple do carry some of the blame.

    I have a lot of wifi interference round here and have been fighting network dropouts for several years – initially on an entirely Windows network with no Apple components at all. I’ve tried a variety of access points – they all suffer from it on occasions. I don’t think it is totally due to interference either – we are working at high speeds on microwave frequencies here and the connection simply breaks from time to time – interference simply makes it much more likely.

    Windows machines drop out just as frequently as Macs, non-Apple access points drop out as well as Airports – the difference is that they seem to recover far more quickly – if you are not actively monitoring the connection, you are not aware of it – throughput just drops off for a couple of seconds.

    Carefully selecting a channel as described above will help a lot, but Apple really need to put in the effort on their firmware and network stacks to make them as resilient to interference and wifi dropouts as Windows already is.

  21. Morgan says:

    Thanks for this, and for pointing out AP Grapher. What a cool tool. Seeing the other 9 wireless networks in my area and what channel they are on is great. After switching my settings, I’m cooking along great right now – let’s hope it lasts.

  22. Brian says:

    Really helpful – thanks! I brought a laptop home from work and could not sustain a connection for more than a few minutes. Densely populated here in Amsterdam, AP Grapher revealed no less than 45 competing networks! After some experimentation I found that channel 9 works well for me. Took a lot of googling to find this info, I’m surprised it’s not more widely known.

  23. Fernando says:

    Hi, tthank you very much I have been having problems with this same issue, it has been making me and my wife crazy, i did everything from changing all parameters using airport utility but nothing worked for more than a few hours, after that it didn´t work at all, I noticed my airport is receiving signal from new networks so I figured out that you idea of changing channels could work, so now I´m enjoying my connection again, I set my channels to 9, and is working flowlessly, thank you again, also the reccomended AP grapher is very useful, thank you again…

  24. Flashbax says:

    I am totally having the same problem with the dropouts. I set my channel to 9 and have a much better signal. But what do you do when you don’t have access to the routers channel. I am constantly dropping the signal at school. I wonder when Apple will fix this issue!

  25. Daniel says:

    Saved my ass there pal. A million thanks!

    //D

  26. Ged says:

    Glad this post has helped so many people. I anxiously await the day when we have a better solution, but for now, these work-arounds will have to do. Stay frosty everyone!

  27. Wouter says:

    Wow, this really helped. No dropped connection for 48 hours. Luckily, around me, there is no one on channel 1!
    Thanks!
    Now, when will the macs be improved so this is not necessary? I have 3 PC’s at home on the same router and they NEVER dropped out, even with local interference. I switched to Mac to avoid such hassles!

  28. johnny says:

    I’m having a problem with airport dropping signals, but it seems to be a little different. To start with, I can often times not get any signal when sitting right beside a pc with full signal strength. What is more annoying than this is when I go somewhere, (specific locations, and we’re talking room sized areas) and airport gets full signal, but then slowly drops from 5 bars to 4 to 3 to 2 to 1 to none. I can surf the internet for the three or four minutes I have a signal, but then it is gone. If I restart the computer, the process repeats. Also, there is one spot in the library where this happens if I put my computer on the chair, but if I have it on to the table it is fine. However, if the laptop loses the signal on the chair first and I then move it to the table, it won’t get a signal until restart. What is going on?

  29. johnny says:

    oh, I suppose this is about airport extreme, huh? I should read more before I post. Does anybody have any clue about my problem despite the fact that it’s on the wrong page?

  30. Danny says:

    Very nicely done! I had no idea that automatic channel selection wasn’t re-negotiated between clients when the channel became noisy.

  31. Roger says:

    I’m still experimenting with changing channels, but one thing I’ve found is that making the network unsecured (i.e., no password) eliminated all issues I’ve had with dropping connections. Granted, this is not a viable solution for everyone, but using an unsecured network in conjunction with the ‘closed network’ setting may be an acceptable workaround until Apple provides a solution.

Trackbacks

  1. [...] larger. Letting bugs slip through the cracks must be a lot easier these days. Update: Looks like someone may have found the culprit behind the intermittent WiFi drops in Leopard (automatic broadcast channel). I’ve set my [...]

  2. [...] any case, this article had an interesting point : Basically, interference from other wireless APs in the area, was probably causing the drop outs. [...]

  3. [...] Maheux of The Iconfactory (and friend of TUAW) has found a possible culprit … plus a solution that works for him, and hopefully for you [...]

  4. [...] gedblog » Blog Archive » Solving Airport’s Mystery Dropouts Ever since Christmas of 2007, I’ve had a problem. Sudden, seemingly random Airport signal dropouts. These frustrating gaps can last anywhere from a few seconds to minutes or even hours. (tags: airport mac troubleshooting wifi networking osx howto) [...]

  5. [...] Maheux of The Iconfactory (and friend of TUAW) has found a possible culprit … plus a solution that works for him, and hopefully for you [...]

  6. [...] Gedeon Maheux, a designer, reported the problem on his blog in late Feb. Being at the end of a dead-end street, I always assumed we were pretty isolated from interference from other networks. When we first moved in, my Airport network was alone in the neighborhood. But sure enough, a quick check with AP Grapher this week revealed between 6 to 8 other WiFi networks. After a walk around the development, and chatting with neighbors, I was able to create a rough map of the wireless networks that surround our home. [...]

Speak Your Mind

*