If you're using a 802.11ac WiFi device, you may want to avoid 80MHz channel width
This was a strange networking challenge I recently faced, something I just couldn't find documented anywhere. Perhaps this article will give some folks in similar circumstances something to try, if they experience similar WiFi flakiness. In my case, what I mean by flakiness was using Safari or Chrome on my iOS 8.1 iPhone 6 Plus, where roughly 1 in 5 attempts at browsing would result in a stall about 20% into loading a requested web page. Waiting wouldn't help, it'd also never finish. When I refreshed, it might load, or it might not. Try again about 30 seconds later, and it'd act all normal, loading the page very quickly. Heading off to the Mail app, same deal, might work, might hang when trying to refresh my Inbox. Hmm...
Yep, I knew this could be a tough one to fix. Perhaps an early-adopter issue, I'm used to those. As usual, persistence paid off, and was key to squashing this bug.
You see, this was my home's first 802.11ac capable WiFi client device. Even during the initial setup, I quickly noticed problems with WiFi. I mean, I didn't even get past the initial questions about restoring my iPhone from iCloud without multiple time-out sort of warnings about my WiFi not working, as it tried to use my 5GHz channel of my Linksys EA6900 802.11ac WiFi router. This was aggravating, and a bit worrisome, as I began to think it might be the actual phone, especially resetting it to defaults didn't help, and since my device seemed to be experiencing the issues far more often than the other iPhone 6 Plus devices in the family.
I was stopping by the local Apple Store for a case anyway, so I made a Genius Bar appointment before heading over. The Genius and I quickly checked my surfing abilities using the store's Apple WiFi. Of course, it worked fine, consistently. The Genius then asked the basics, like was I too close to the WiFi router, or too far. I politely explained the speed and signal was excellent, and the WiFi indicator was staying locked on just fine. It's the flow of TCP/IP traffic over the connection that was halting intermittently. Of course, without being able to replicate the issue in the store, I knew my work was cut out for me back at home, figuring out what setting(s) in my router were to blame. Likely some deviation from factory defaults.
When back home, I opened a ticket with Linksys support. Why bother? Well, the way I was seeing things, it was worth communicating with them, since their forums had no useful/relevant posts on this issue. Also, just in case they had heard of this issue, perhaps they could explain a fix or workaround. After providing proof of purchase, it was immediately clear that I was at 13 months of ownership. This meant I was out of warranty. I convinced them to try to work with me on a best-effort basis, and they did. But of course, they simply had me reverting to factory defaults, then reconfigure all my settings manually (port forwarding, security hardening, etc.) Wasn't particularly interested in leaving my network at defaults, so I saved off the config for later restore. But at factory defaults, I could see that the WiFi problem went away. Progress.
I also checked with the always-excellent Apple Support folks, who didn't have any big known-issues with 802.11ac that they were seeing that could really help me, but were very interested in following up with me. It'd help me, Linksys, and Apple to get to the bottom of this. I promised to let them know about the resolution, so perhaps they'll be better equipped to handle other folks asking about the same sort of issue.
With those phone calls behind me, I knew I was getting warmer, that it must be about some settings that affect just the 5GHz band in my router that was different than factory defaults. I then found this hint, and post that give me the "a hah" insight into which setting I needed to look closely at:
Apple Support Communities - iOS 8 Wi-Fi problems by seansekora on Oct 07 2014:
I was having the same wifi problem with my iPhone 6. I changed the following settings on my router and it started working.
Wireless Band: 5GHz
Network Mode: 802.11a/n
Channel Width: 20 MHz only
Security Mode: WPA2 Personal (AES)
And here is an Apple document with a couple other settings iOS and OS X: Recommended settings for Wi-Fi routers and access points
Admittedly, this wasn't a spot-on match for my situation at all. It didn't even talk about 802.11ac actually. But it was a clue.
Since I didn't want to limit myself to a measly 20MHz, I figured, how about I just tinker with my WiFi settings, focusing on the 5GHz channel width setting, trying "Auto" to see if things get stable. Yep, that did it alright. Did a whole bunch of tests actually, trying various tweaks that I tracked in a simple Excel spreadsheet that you can see in OneDrive here, including all the relevant testing procedure details.
After all that testing, turns out only that one simple change mattered, as far as stability. Moving my 5GHz WiFi Channel width setting from "80MHz" back to factory defaults of "Auto," immediately, all iPhone Plus phones were stable. And super fast, see Speedtest.net Mobile Speed Test App screenshot. Ta da! Angels sang, and all was right in the household again, time to really just enjoy these amazing new phones, and go back to other weekend projects.
Step-by-step fix for my Linksys EA6900 WiFi Router
- Log in to the web UI, typically for most users, it's
http://192.168.1.1 - Head over to WiFi (the Wireless button 2nd from the bottom)
- Next to the "5 GHz network" click on "Edit"
- Change "Channel width:" to "Auto"
I suspect this sort of 802.11ac issue may affect not just Apple and Linksys device owners, so I'm hoping this article helps other folks as well. Let us know by dropping a comment below!
See also
How to speed up your home’s WiFi speeds by testing the best 2.4GHz and 5GHz WiFi channels
by Paul Braren on Nov 16 2014
Linksys EA6900 802.11ac WiFi Router security best practices
by Paul Braren on Feb 23 2014
Firsthand experience with ASUS RT-AC68U, Netgear R7000, and Linksys EA6900 802.11ac WiFi routers
by Paul Braren on Oct 05 2013
Update May 13 2015
See the very interesting feedback from my friend in the comments below, encouraging me to give dd-wrt firmware another try, and indicating that this same behavior is seen on the Asus RT-AC68R and the NETGEAR R8000. Wow!
TinkerTry.com/if-youre-using-a-802-11ac-wifi-device-you-may-want-to-avoid-80mhz-channel-width#comment-1939412271
All Comments on This Article (34)
This inspired me to change the channel on my router. My Galaxy S8 was only connecting at 20mhz (link speed around 170mbps). When I changed my router's channel from auto to something like 148, the phone now connects at 80mhz around around 833mbps!
If you want 80 MHZ channel width, channel setting is crucial. Main focus is to choose non-overlapping channels, it is described in the link: http://www.revolutionwifi.net/revolutionwifi/2013/03/80211ac-channel-planning.html
A quote from the article: "For example, if attempting to guarantee non-overlapping 80 MHz channels,
limit the allowed subset of primary 20 MHz channels to 36, 52, 100,
116, 132, and 149. The specific 20 MHz channels could be different than I
have listed in this example, but the key point is that only ONE primary 20 MHz channel be allowed within each "guaranteed" wider channel width."
I am from Europe, so the only option for me is channel 36. (given the region, the router I have and the choice of avoiding DFS channels)
Also slide 4 in the next link https://www.slideshare.net/mjarski/80211ac-overview has a pic which is self explanatory for choosing 40Mhz or 80Mhz width. Hope it helped, considering how late I found this post.
Sorry, not sure, older article, not using that WiFi router in my home anymore.
That's pretty good for the distance, but what do you get same room?
WiFi to LAN I get around 400Mbit on 80Mhz with an Intel 7260.
I use a TP-Link Archer C7 v2 with OpenWRT for WiFi duty only, as at 400Mbit traffic the CPU is pretty much maxed out.
Thanks for the updated info!
What you've said makes sense to me, thanks for sharing. My strangeness was likely just a moment in time, with the firmware I had at the time.
It would seem my new eero (which is admittedly much more costly):
https://TinkerTry.com/replaced-linksys-with-eero-after-also-testing-luma
is doing 80MHz, given I'm seeing around 140Mb/s in my home, in all rooms that I care about.
I know this is an old discussion, but I need to add 2¢. Just had gigabit fiber internet installed yesterday and I've been fine tuning an ASUS RT-AC3200 with Tomato v138. On the other side, a laptop with Intel 7260 ac wifi card. Devices are about 50' and four walls apart.
On 5GHz channels, the throughput (using Speedtest.net) doubles with doubling of bandwidth. I'm getting about 35Mb/s at 20MHz, 70Mb/s at 40MHz, and 140Mb/s at 80MHz. Just as expected using 802.11ac. Connects fine with handhelds, too. No dropout problems at all.
My advice? Heck yes, use 80MHz bandwidth.
I"m sorry, I no longer use that router on a regular basis, and not sure if the defaults changed after I had updated to the last firmware update they released. I hope somebody spots this and can answer your question.
Great article! I'm slightly confused though. The article states that the factory defaults for the Channel Width on the 5GHz network is "Auto". I also have the EA6900 router (v1.1), but when I reset mine to factory defaults (through the admin pages or button), it goes back to 80MHz. Does anyone know anything about this, or have the same behavior? Perhaps the default value has changed with one of the firmware updates? I am using the latest version and noticed that it was released six months before this article was posted, so I'm not sure if it's that. The release notes had no mention of it either. I'm just baffled. Any reason why Linksys could have changed the default to 80Mhz?
Excellent, glad this old article still has some value, and that you found it! Hope you like other network related stuff here too:
https://tinkertry.com/category:Network
You are the man! I have tried everything to get the 80m channel working on the 5G but without any use. using channel 48 changed everything for me and made my 5G connection as fast as I could hope without even dropping any connection! Thank you really man and I hope people with similar issue can find your advice here.
Glad to hear this 15+ month old article is still helpful! Kind of can't believe this issue is still "a thing."
Thank you for stopping by and leaving a comment.
I can confirm this solution worked with an Arris SBG6900-AC cable/modem combo on twc 200 mbp/20 service using the 40 mhz channel with an iphone 6s plus. Thank you for the post!
Wow, thank you for sharing your story, much appreciated. Nothing simple about this topic, but glad I shared my experience, which has apparently helped others.
Thank you for this info. I have being using my Nexus 5X for almost a week and was pretty worried about its WiFi performance, it was really bad. It took forever to load videos on chrome and even if it started it stopped every couple seconds. I have a cheap TP Link WR841N for my room with DDWRT, but the firmware wasnt updated for some time. I tried a newer firmware but no difference. I came here and tried a different channel width. My router was setup in 20 MHz and I switched to 40 MHz and my Nexus 5X is now working fine. Still high latency but probably I need a better router to get rid of that.
Interesting, thank you for the UK perspective and information!
Here's a product link:
http://store.virginmedia.com/discover/broadband/explore/our-fastest-wireless.html
for those interested in this device.
So, where's somebody from Germany, chiming in about their Fritz WiFi router? ;-)
https://twitter.com/paulbraren/status/516197075344973824
Worth noting, 80Mhz works fine with iPhone 6, Macbooks etc on the Virgin Media Superhub AC. It did not work on my old Linksys router, I blame the router manufacturers not the devices therefore.
I sure do appreciate your taking the time to share your story, with wireless so much more complicated than we'd like.
So I switched the network to channel 48 on the 5GHz band, but that caused my signal to plummet and the peak link speed went way down. (To make sure the Mac was reading the link speed correctly, I switched to Windows 10 Boot Camp and checked the speed there as well). I was hitting over 200Mbps on Win 10 before selecting the band, but that went way down with the 48 channel. Instead I just set it to the 40MHz option, and now it has switched over to channel 157, which seems to be avoiding the 7Mbps problem. Now in Mac I get speeds from 88-176Mbps, which is fair considering my Internet speed itself is 90Mbps. So for now, 40MHz appears to be the way to go. I'm hoping Asus will update this with firmware because not being able to use 80MHz fully is a shame in a high-end router.
Wow, interesting story, thank you for sharing. I will be curious to see how it turns out for you.
I've been using an RT-AC68P (the one with the faster CPU) and I've noticed issues where the 5GHz will drop down to a link speed 7Mbps and be very unresponsive unless I switch to the 2.4GHz band. I haven't been able to find any posts on this online, but moving just one room over to a floor above the router brings the speeds to well over 500Mbps, even to over 800 at some points. It was going to channel 149 and 80MHz on Auto so I moved it to 48 and 80MHz as suggested and I will see how it works. From where I am, there are no other 5GHz networks detected by my computer.
Great news Paul. Exactly, the stalling should be absolutely gone. I'm glad you were able to confirm my results. You're the first person I've mentioned this to because you're the only one that described the issue so clearly, but I suspect that many of the other similar issues I've seen around the web are caused by the same thing. For example, the 5ghz ssid not appearing in the list at all.
Anyway, to answer your question in mid Feb 2014 I bought an Asus RT-AC68U. Initially it didn't have issues - but then I noticed some issues later in 2014 but I've been busy as a new father (son just turned 9mos) and I haven't had a chance to really look into things until now.
See also informal tests I did for my home, back when choosing a channel:
"How to speed up your home's WiFi speeds by testing the best 2.4GHz and 5GHz WiFi channels"
https://tinkertry.com/how-to-speed-up-your-homes-wifi-speeds-by-testing-the-best-2-4ghz-and-5ghz-wifi-channels
All great points. I did do some testing with a borrowed Surface 3 running Windows 10 (at 802.11ac) and the speed tests didn't show a difference between my 9 month setting of Auto/Chl 44, and the test you proposed of 80/Chl 48, but like you had stated, it should be stable (not stalling) at 80MHz this time instead of stalling, and you were right! So, which AC router did you go with?
Thanks Paul. Look forward to your results. Of course, you're not likely to get better internet speeds unless you have an extremely fast internet provider.
However, if you're like me the reason I paid $270 for my AC router was so I could have the faster AC speeds - so it was unacceptable to me that my router would be unable to operate on 80mhz (which represents the true AC band) because that's what I ponied up the extra cash for.
I do backup my PCs to a central ZFS NAS so I definitely enjoy reduced backup times. My mac connects at 866mbps and my Toshiba is even faster than that. The speed increase will be seen on the LAN, not the Internet of course, unless you have an AWESOME internet provider. And 2.4ghz will provide better range but I use 5ghz for the awesome AC bandwidth because AC doesn't work on 2ghz.
My router can support up to 1300Mbps if the client device can handle 3 streams. Each AC full stream is 433 Mbps, so 866 tells me my Mac is capable of 2 streams.
Richard, this is an incredibly detailed and thought out response, it's great having folks like you stop by. Since I wrote this article 9 months ago, 5GHz has been very solid, but if trying what you suggest actually gives me higher speed test results on http://www.dslreports.com/speedtest and http://www.speedtest.net/ as well, that could be interesting. I realize there are better tests for on-network PC to PC communications, but those are exceedingly rare, basic internet speed testing is more relevant for my family. I'll reply with results, once I get a chance to try this out. Thank you!
Hey man I was having the exact same issue you describe. I have seen a million different solutions to this problem... But they all work only temporarily unless you cure the root issue. The root issue is channel selection. 20mhz requires one channel, 40mhz uses two channels and 80mhz uses 4 channels. The more channels, the more speed. By selecting 40mhz you're probably just giving yourself a better chance of not getting on one of the bad channels.
Bottom line - based on countless hours of research - I traced this behavior to DFS in the 5ghz band. It's a new "feature" but it doesn't work well whatsoever.
Basically, it allows your router to use the same channels that weather and airplane radar use, as well as military and emergency channels.
However - if your router OR client device detect any activity on those channels, they will immediately stop talking on the channels and (hopefully but probably not) will renegotiate to a different channel which will interrupt your connection over and over again unless you live underground or in the middle of literal nowhere. Devices can detect radar up to 30 miles away, and God help you if a neighbooe has their router set to an incorrect region code because your devices will thing they are in another country (if they hear that region becon first) which will confuse things further
In summary: you must not use DFS channels for the time being until the industry sorts these issues out. That means you cannot allow your router to auto select a channel.
To see if this is your issue, simply select 80mhz band and channel 48 which is a non DFS channel. Also, if you can enable regulation mode 802.11d - that can help also. Give it a shot. I have 4 laptops- a toshiba, dell latitude, dell xps, MacBook Pro; two iPads; an iPhone 5s, iPhone 6. And Apple TV that are all on 5ghz AC with absolutely no problems now.
And I was exactly where you were when I started.
For me, DD-WRT runs until I have to unplug the router or I'm trying to diagnose a problem (that has never turned out to be the router's fault). Uptimes over a year. I did take down one of the APs, had a router and two APs spread throughout this non microwave friendly old house, because it kept dropping connections... and it's near the microwave, which was causing audio issues with my new Bluetooth headset. Fairly new Panasonic microwave too, less than a year old, full-size high wattage model though. I should set that AP up again and try tweaking the settings as you describe. I had guessed that hanging the AP off a dumb switch that's hanging off the router was a bridge too far, which still might be the case.
So great to hear from you! (I briefly read this post the other day from my cell, and didn't actually notice the name until just now).
Stephen, I don't really know the root cause, and haven't given it much thought since writing this, honestly. But I will say things have been pretty stable here, and at 2 other extended family homes, running this same modem/firmware. So, luckily, I haven't been seeking out alternative firmware really (but I've played with them in the past).
So, I'll ask, how stable has the EA6900 been with DD-WRT? Do you go months without having to reboot the modem, for example?
FYI, just replaced my microwave, amazing how much less RF noise this one is putting out, here's the related post: https://TinkerTry.com/2-4-ghz-versus-5-ghz-wifi-with-microwave-interference
Paul,
Long time no see!
Your diagnosis here is spot on!
I've run into this myself on an EA6900, an Asus RT-AC68R and a NETGEAR R8000.
Any idea what the root cause is?
Also, have you tried DD-WRT on your EA6900? MUCH better than the stock "Smart" firmware from Linksys.
http://www.dd-wrt.com/phpBB2/viewtopic.php?p=951005&highlight=#951005
Download: http://www.dd-wrt.com/site/support/other-downloads?path=betas%2F2015%2F03-19-2015-r26490%2Flinksys-ea6900%2F
Keep in touch amigo!
Stephen
This is the best sort of feedback an article like this can hope to enjoy, and I thank you, alude904, for taking the time to type this up. Also glad you took advantage of Disqus' easy image sharing.
FYI, in the 3 months since I wrote this article up, it's been smooth sailing for my family's iOS and Android devices ever since.
I want to add and confirm with this post's findings. I had the exact same issue and was pretty sure it was the 80mhz spectrum but didnt want to admit it. However my modem/router only has 20/40/80 mhz options. I want to confirm that 40mhz works perfectly fine if you dont have an auto option. I have a motorola surboard sbg6782-ac modem/router with comcast as the isp and the iphone 6 plus. My symptom was also intermittent connectivity. This is the setting on my router i changed.
Good to hear that Apple seems to be doing a swell job to do interoperability testing with their WiFi products, and you make a good point, if you want one company to work with for your iOS device support, an Airport might be very well be the best way to go. Especially when one compares support for Linksys versus Apple, for example ;-)
Folks, if you're hankering for some outside technical support from Apple, to help supplement help in those friends and family homes, consider recommending the 802.11ac Apple Airport Extreme Base Station http://amzn.to/1qCPU92 or with 3TB Time Capsule (for backup duties) http://amzn.to/1xvoBy2
Ultimately, I'm quite happy with my EA6900
http://www.tinkertry.com/ac1900routers/
(which doesn't require reboots for routine port forwarding changes that I mess with )
and my SB6183 cable modem
http://www.tinkertry.com/sb6183/
Especially now that I'm getting amazing speeds, having figured out this WiFi issue that I admittedly got myself into, by changing away from the factory default of "auto" for the 5GHz channel width. Live and learn, and share!
My 802.11ac capable devices play very well with my Apple Airport Time Capsule (both Apple and non-Apple devices).
The Airport Extreme / Time Capsule base stations have a fixed channel bandwidth of 20MHz at the 2.4GHz (offering an air interface of up to 300Mbps) and up to 80MHz channel bandwidth on the 5GHz spectrum, with a staggering air interface speed of 1300Mbps.
The "measly" limitation of using only 20MHz on the 2.4GHz is a very clever idea, as that spectrum band is very crowded as we all know, and allows only 3 non-overlapping channels.
Generally speaking, choosing a channel with high-noise level (which leads to a low SNR) forces both the base station and the mobile device to work on a low modulation (lower air-interface rate or MCS) which means lower speeds and lower throughput; it also increases the Packet Error Rate (leading to more retransmissions).
Even if the channel is partly used due to a slightly overlapping adjacent channel your throughput will still be affected. This is why 40MHz CBW on the 2.4GHz spectrum is a very bad idea (but then again, so is 80MHz CBW in a crowded 5GHz spectrum...)
Paul Braren | TinkerTry.com
Nice, glad to hear this old article still has some value, thanks for sharing your story, mark k!