Resolved Cannot get 300Mbps 802.11n wifi speed on MBA

Discussion in 'MacBook Air' started by oneMadRssn, Jul 11, 2013.

  1. oneMadRssn, Jul 11, 2013
    Last edited: Jul 11, 2013

    oneMadRssn macrumors 68040

    oneMadRssn

    Joined:
    Sep 8, 2011
    Location:
    Boston, MA
    #1
    It seems ever since I had my logic board replaced (I think unnecessarily) my MBA hasn't been able to connect to the wifi at the full 300mbps* speed.

    The router is a Linksys E3000. My 5Ghz wireless is set up with 40mhz wideband, channel 40, WPA2 AES security, WMM enabled. There are no other 5Ghz signals in my building as far as I can see.

    Another computer in my apartment, an aging Dell, is able to connect at 300mbps no problem. So I'm pretty sure the router is not the issue. I ran a modified version of TomatoUSB on it, but last night I reverted back to the stock Linksys firmware and I still had the same issue. Dell at 300, MBA at 150.

    The interesting thing is when I change the wireless settings to be narrowband at 20mhz, the Dell goes down to 150Mbps as expected, but the MBA goes down to 65. Approximately the same signal strength on both computers.

    The only thing I have left to do to narrow it down to the MBA is to take it to a friend's house to test it in a different environment.

    I am still not convinced it isn't some setting in the MBA that I am missing. Could that be it?

    Has anyone else experienced this odd behaviour? Prior to the repairs I linked above, I was able to connect at 300Mbps all the time.



    * I know that when the connection speed is 300Mbps does not mean I will get that speed in the real world. However, I move medium size files over to a NAS sometimes, and the difference between 150 and 300 in the realworld is substantial enough for me to notice and make a difference.
     
  2. Menel macrumors 603

    Menel

    Joined:
    Aug 4, 2011
    Location:
    ATL
    #2
    According to this table WIKI, Channel 38 isn't supposed to be legally allowed in the USA, your Dell and MBA should not have even authenticated, nor should your stock Linksys firmware have allowed it.

    http://en.wikipedia.org/wiki/List_of_WLAN_channels#5.C2.A0GHz_.28802.11a.2Fh.2Fj.2Fn.29.5B15.5D

    Try channel 44. I see a lot of people using it.

    I've heard some channels have a power and bandwidth limitations. Maybe the MBA is honoring and the Dell is not. My Linksys E3000 is setup for "channel: 153 + 151" whatever that means, I configured it a LOOONG time ago with DDWRT and get full speeds.
     
  3. oneMadRssn thread starter macrumors 68040

    oneMadRssn

    Joined:
    Sep 8, 2011
    Location:
    Boston, MA
    #3
    Thanks for that info. To be honest, I'm at work and was trying to go from memory what channel I had setup. I remember it was something low (high 30s, low 40s). I guessed 38.

    I'll try 44. Might try 153 and 151 as well.

    I did note that per the wifi scanning tool in OSX, TomatoUSB was properly reporting the region to beUS, but the Linksys firmware is null in that value.
     
  4. johnjey macrumors regular

    Joined:
    Jun 17, 2013
    Location:
    Northern CA
    #4
    My ISP is one of the worst in US as they have 100GB download limits per month & my ISP data limit will literally explode i guess if i buy the Airport Extreme after hearing your conversation about 300mbps speeds
     
  5. oneMadRssn thread starter macrumors 68040

    oneMadRssn

    Joined:
    Sep 8, 2011
    Location:
    Boston, MA
    #5
    I tried those channels. Same issue :-( MBA still 150Mbps... Dell still 300Mbps.

    For anyone else with some ideas, here are some screenshots:
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  6. oneMadRssn thread starter macrumors 68040

    oneMadRssn

    Joined:
    Sep 8, 2011
    Location:
    Boston, MA
    #6
    .... and it's fixed .... once again showing that "Apple Genius" is a huge misnomer to say the least.

    As you can see, after replacing my logic board, one of the antenna wires was completely unplugged. That picture below is exactly how I just found it after opening the case.

    Thanks Apple. Good thing everyone has a pentalobe screw driver in order to open their Macs and double-check that the Genius (now I'm using it sarcastically) plugged in everything that needed plugging in.

    Seriously, an unplugged wire was the last thing I expected. I opened the case to see if reseating the wifi card would fix my issue.

    [​IMG]

    [​IMG]

    As an aside, check out that planet-sized glob of thermal paste. Eesh, I'll have to redo that another time.
     
  7. old-wiz macrumors G3

    Joined:
    Mar 26, 2008
    Location:
    West Suburban Boston Ma
    #7
    jeez....is it that difficult for the Genius to re-attach all the wires?
     
  8. TC25 macrumors 68020

    Joined:
    Mar 28, 2011
    #8
    Did the genius do the actual board replacement?
     
  9. oneMadRssn thread starter macrumors 68040

    oneMadRssn

    Joined:
    Sep 8, 2011
    Location:
    Boston, MA
    #9
    Aaaallll the wires? *groan*

    I am not sure who exactly qualifies as "genius", but the repair was done at the Boylston St. Boston store. There was the guy who check-in my mac and did the initial evaluation, and there was another guy who came out of the backroom once to twice to confirm that he did have a logic board in stock, and that he did have time to do the swap overnight. That second guy did say he would be the one to do the actual swap, not sure what his official title is, but the evidence shows he's certainly no genius.
     

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