Reduced 5GHz wifi speeds with USB 3.0.

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Reduced 5GHz wifi speeds with USB 3.0.

I have run into an annoying issue and am looking to get some feedback before calling apple support. On my Mac Pro (Late 2013) [cylinder version], the normal wifi speed with my router is 1300/1300 mbps. This is because they are in the same room. I get a very decent wifi through put between a network file share and the computer. However, the wifi speed is reduced by the MacPro to 867/867 (2x2) when a USB 3.0 storage device is plugged into the mac pro. This reduced link speed also reduces the wifi throughput. This problem persisted in OS X 10.10 and was fixed in OS X 10.11 until 10.11.3 update which the problem re-surfaced.

Its easy to replicate the problem, just plug a USB 3.0 storage device to the USB 3 port/hub and the wifi speed drops. So, is anyone else seeing this issue ?

Mac Pro (Late 2013), OS X El Capitan (10.11.3)

Posted on Jan 20, 2016 3:34 PM

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Answer 1

lllaass

Level 10

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Jan 20, 2016 3:48 PM in response to sriname

http://www.macobserver.com/tmo/article/usb-3.0-hard-drives-can-cause-wi-fi-inter ference

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Answer 2

sriname Author

Level 1

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Jan 20, 2016 4:27 PM in response to lllaass

Hi, thanks for the response. Yes, this is well documented on the 2.4GHz band. Intel had put out paper documenting the interference. However, there is wasn't any known issues about this affecting the 5GHz bands. I believe this is a driver issue because when 10.11 came out this problem went away. OX 10.11.3 update came out a few days ago, the problem re-surfaced leading me to believe that the driver changes is the cause.

http://www.usb.org/developers/whitepapers/327216.pdf

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