If you're using a 802.11ac WiFi device, you may want to avoid 80MHz channel width

Posted by Paul Braren on Nov 16 2014 (updated on May 13 2015) in
  • Network
  • 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.

    Oct 29 2014, on 802.11ac

    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

    1. Log in to the web UI, typically for most users, it's
    2. Head over to WiFi (the Wireless button 2nd from the bottom)
    3. Next to the "5 GHz network" click on "Edit"
    4. 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!