XavierXing

Q: 5G wifi linkspeed is slow (11Mbps)

I don't know this starts from when, and I'm not sure whether this is a problem of the router or of my mac, because those are the only two devices with 5G wifi hardware, so there's no way I could do cross-check.

It used to be very fast, I could transfer between my mac and my nas (attached with Gbps cable) at 100MB/s, at that time the autoconfigured linkspeed is 1300Mbps. Now the transfer rate is at max 3MB/s. What a big difference!

 

I've tried rebooting the router, rebooting the wifi, delete the wifi profile and reconnect, all sorts of basic operations. I'm not very familiar with wireless router engineering (not very familiar with telnet commands), so please help me with this. Is there anyway to locate the problem?

 

I am using a Macbook pro 13' 2015, the OS is el capitan 10.11.1. And the router is R6300v2 with the newest firmware (which is flashed very long time ago, long before any problem arises)

MacBook Pro with Retina display, OS X El Capitan (10.11.1)

Posted on Dec 11, 2015 7:10 PM

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Q: 5G wifi linkspeed is slow (11Mbps)

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  • by Duane,

    Duane Duane Dec 11, 2015 7:30 PM in response to XavierXing
    Level 10 (124,018 points)
    Dec 11, 2015 7:30 PM in response to XavierXing

    When you say "5G" I assume that you mean "5GHz". Is that correct?

     

    Have you made any changes to physical structure between the MacBook Pro and router? 5 GHz has a lower ability to penetrate objects and has a lower range than 2.4 GHz.

     

    Have you tried using other 5 GHz channels?

  • by XavierXing,

    XavierXing XavierXing Dec 12, 2015 4:36 AM in response to Duane
    Level 1 (8 points)
    Mac OS X
    Dec 12, 2015 4:36 AM in response to Duane

    Thanks~

    Yes I mean 5GHz;

    And nope, Not any physical changes have occured, same old room, the router stayed put for a long time and already has dust all over.

     

    Yes I've tried other channels, formerly using 153 and tried 161. I also saw in a certain software that there are four available channels (149,153,157,161), all of which are empty, looks like I have the only 5GHz router in the neighbourhood.

     

    I had the router turned off for half a day, but after turned back on the problem persists. Everything else is perfectly stable except for the linkspeed of my mac.

     

    I've also tried turning of the 5GHz radio and connecting through 2.4GHz, in this case my mac still gets only 11Mbps (super strange!); My old android phone, in compare, has a linkspeed stably at 72Mbps.

  • by Duane,

    Duane Duane Dec 12, 2015 9:06 AM in response to XavierXing
    Level 10 (124,018 points)
    Dec 12, 2015 9:06 AM in response to XavierXing

    Have you tried switching to 2.4 GHz?

     

    How are you checking for other wireless signals in the area? I find the app "WiFi Explorer" to be informative.

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Dec 12, 2015 9:14 AM in response to XavierXing
    Level 9 (60,936 points)
    Desktops
    Dec 12, 2015 9:14 AM in response to XavierXing

    Hold down the option key and click on the Wi-Fi Icon in the MenuBar. You get a display similar to this one:

    Option-WiFi.png

     

    what do you get for PHY Mode and Channel?

    What do you get for RSSI/signal strength?

    what do you get for Transmit Rate?

     

    and most important, what does it say for how many other networks are visible?

     

    I am fishing, in this case, for poor performance due to weak signal, with a thought that perhaps your antenna lead is disconnected or damaged (in some models, the wire passes through the hinge area and is subject to chafing).

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Dec 12, 2015 9:25 AM in response to Duane
    Level 9 (60,936 points)
    Desktops
    Dec 12, 2015 9:25 AM in response to Duane

    Hey Duane--

     

    did you know about Wireless Diagnostics, available from Option-clcik the Wi-Fi Icon ?

     

    Use Wireless Diagnostics to help you resolve Wi-Fi issues on your Mac - Apple Support

     

    it can be left running in the background and send you an Alert when something changes. Not well defined in that article, while it is doing that, it can also put up some graphs:

     

    Wi-Fi scan.png

    click for full size

    Wi-FiPerfomanceGraph.png

    It can also capture packets, if you have some use for that.

     

    .

  • by Duane,

    Duane Duane Dec 12, 2015 9:38 AM in response to Grant Bennet-Alder
    Level 10 (124,018 points)
    Dec 12, 2015 9:38 AM in response to Grant Bennet-Alder

    That looks like it has more capability than I thought. But I find WiFi Explorer has tons of useful information presented in some great formats.

     

    WiFi ExplorerScreenSnapz001.png

  • by XavierXing,

    XavierXing XavierXing Dec 12, 2015 6:06 PM in response to Duane
    Level 1 (8 points)
    Mac OS X
    Dec 12, 2015 6:06 PM in response to Duane

    Screen Shot 2015-12-13 at 09.20.38.pngScreen Shot 2015-12-13 at 09.28.19.png

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Dec 12, 2015 8:18 PM in response to XavierXing
    Level 9 (60,936 points)
    Desktops
    Dec 12, 2015 8:18 PM in response to XavierXing

    That says you are using an 80MHz wide channel using 802.11ac, potential speed 1300bits/sec. Your signal /noise is very strong, and competition on that channel appears to be none.

     

    But your transmit speed is only 54Megabits/sec. Something is wrong, but I do not see what it is.

  • by XavierXing,

    XavierXing XavierXing Dec 12, 2015 10:20 PM in response to Grant Bennet-Alder
    Level 1 (8 points)
    Mac OS X
    Dec 12, 2015 10:20 PM in response to Grant Bennet-Alder

    Is there anything else I can test?

  • by Duane,

    Duane Duane Dec 13, 2015 8:02 AM in response to XavierXing
    Level 10 (124,018 points)
    Dec 13, 2015 8:02 AM in response to XavierXing

    I was comparing your numbers to what I see. I am only using a 2.4 GHz network but I noticed my MCS is 15 and yours is 0. This is an indication that you should expect bad performance. Here are some links with info on the MCS -> http://www.wlanpros.com/mcs-index-802-11n-802-11ac-chart-3/, http://www.digitalairwireless.com/wireless-blog/recent/demystifying-modulation-a nd-coding-scheme-index-values.html

     

    If I were you I would try changing the channel and changing the bandwidth used. Maybe a wider or narrow bandwidth would improve your data rate.

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Dec 13, 2015 8:26 AM in response to Duane
    Level 9 (60,936 points)
    Desktops
    Dec 13, 2015 8:26 AM in response to Duane

    Modulation schemes (represented by that MCS number) are ways to get multiple bits of data into one signaling interval. Historical ways (lifted directly from telephone-line modems) are using ever more complicated (but recoverable) combinations of phases and amplitudes to produce as many as 256 different recognizable patterns (combinations of phases and amplitudes) in one signaling interval.

     

    This "trick" (and it's a big one) works really well with strong signals with no noise and no interferences from other devices. As the signal quality deteriorates, the Hardware falls back to simpler modulation, say, 16 patterns instead of 256 patterns, so that you can recognize them easily in the existing (noisy) conditions. Then it falls back to four patterns. then one. then it slows the overall speed as well as using the simplest pattern. then it slows further. this is represented by the MCS number dropping from most complex (typically 15) to absolute simplest (MCS 0).

     

    What you are seeing is: on  a channel that is practically ideal, your Hardware has dropped back as if it were seeing massive interference. I have no detailed ideas about what could be causing that. The only way I can think of that could happen is if your Hardware is BROKE!

  • by leroydouglas,

    leroydouglas leroydouglas Dec 13, 2015 9:24 AM in response to XavierXing
    Level 7 (23,571 points)
    Notebooks
    Dec 13, 2015 9:24 AM in response to XavierXing

    While under warranty, I would take it in for a 'Apple Service Diagnostics' testing. Hopefully it is a definitive diagnosis of your WiFi, antenna, cable connection; and you generate a case number for the record.

     

    Genius reservation http://www.apple.com/retail/geniusbar/

     

    on-line https://getsupport.apple.com/GetproductgroupList.action

     

    check warranty https://selfsolve.apple.com/agreementWarrantyDynamic.do

     

     

    On 5GHz you can expect  MCS index higher than 15

     

    pic.png

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Dec 13, 2015 10:42 AM in response to Grant Bennet-Alder
    Level 9 (60,936 points)
    Desktops
    Dec 13, 2015 10:42 AM in response to Grant Bennet-Alder

    To help decide whether this is a broken MacBook or a broken Router, please go away!

     

    go to your Apple Store or somewhere where it is important to have really Fast Wi-Fi.

     

    Note that some commercial operations such a Schools use 802.11a, which uses many overlapping Routers in the 5GHz band, but simple modulation that tops out at 54Mbits/sec.

  • by XavierXing,

    XavierXing XavierXing Dec 14, 2015 12:59 AM in response to Grant Bennet-Alder
    Level 1 (8 points)
    Mac OS X
    Dec 14, 2015 12:59 AM in response to Grant Bennet-Alder

    I can't believe the problem is solved by simply factory-resetting the router....

     

    Now I'm back with 1300Mbps

     

    Thank you guys for all your help~

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