Slow WiFi on an iMac ...

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Slow WiFi on an iMac ...

My Lenovo laptop (running Windows 7 64bit) connects to a WiFi router (a D-Link 655) at our house and has excellent speeds: 33 to 35 Mbits/sec down and 5 Mbits/sec up consistently (as reported by speedtest.net) using Comcast cable Internet service.

But our 14 month old 27" iMac right near the laptop fluctuates between 3 to 12 Mbits/sec down and 5.3 to 5.5 Mbits/sec up (the up speed is very consistent)! An older 13" Macbook shows 21 to 25 Mbits/sec down and 5.5 Mbits/sec up (although I would expect that to be slow - it is not 802.11n capable, as I recall).

When we boot the iMac into Windows 7, we have the same low download speeds and fluctuations, although upload speed is still fine. Thus, I am also speculating that it is likely to be the hardware rather than any software driver problems.

I tested with another WiFi router (a new Netgear WNDR4000 with 802.11n) and the iMac shows the same slow download performance on it as well, although the Lenovo does just great on it!

The limitation appears to be the WiFi connection between the routers and the iMac - but curiously only on downloads(?).

What should we be testing or looking at to improve the download performance of the iMac? Should we get the hardware looked at and tested? Is the Aluminum case blocking signals to the antenna (although the signal strength in Windows 7 on the iMac is "Excellent")?

iMac, Mac OS X (10.7.2)

Posted on Jan 29, 2012 11:10 AM

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Answer 1

John Galt

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Jan 29, 2012 11:38 AM in response to szhosain

This should not happen.

Try this: Go to  > System Preferences, select Network, click the lock to authenticate if necessary, then select Wi-Fi on the left and click Advanced.

Assuming that "Remember networks this computer has joined" is checked, you will see a list of all the networks your iMac has ever joined. Delete all of them by selecting and clicking the "-" button below. OK and then Apply and then you can close System Preferences.

At this point your iMac will be disconnected from your wireless network. Click on the AirPort icon on the upper right of your screen and select your network. Make sure it's the right one! Authenticate if necessary. Your iMac will now be connected again.

If it is still slow I would begin to suspect something is amiss with its internal AirPort card or antenna connection. Its aluminum housing is not an issue.

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Answer 2

szhosain Author

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Jan 29, 2012 12:03 PM in response to John Galt

Hi, John.

Thanks for the response! I will try what you recommend above.

However, I should also note that my son just found another long discussion thread discussing this same exact issue with the WiFi connection on an iMac: https://discussions.apple.com/thread/2344256?start=0&tstart=0.

It seems that we are not unique with this problem! I am concerned that the software fixes mentioned in there are not really the solution, since we experience the same limitation with Windows on the iMac (i.e., different driver!).

The only suggestion from that long thread, that has seemed to work for us, is turning the iMac so that the back of the iMac faces the router. Then the performance jumps up to around 18 to 22Mbits/sec (but not to the higher speeds of the Macbook or my Lenovo). Of course, this is not practical, since the computer faces away from the front of the desk then!

Yes, I would be willing to get Apple to change the internal card out, but from that longer thread, it appears that this is not necessarily the correct answer either.

If all else fails, I will move this desk and computer to another location in the house, where I can direct-connect the Ethernet jack to the router usign a cable and completely avoid using WiFi entirely. Not the best solution, since the other location is not where I need this computer to be, but if that is what I have to do, then so be it. 😟

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Answer 3

szhosain Author

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Jan 29, 2012 2:42 PM in response to szhosain

Hi, John.

I tried removing all the remembered networks as well as removing the location (as mentioned at another site).

Removing all the remembered network did not change anything, but changing the location temporarily increased the speed. It jumped up to 22 to 24 Mbits/sec, but is slowing down steadily. As of my last test (where my Lenovo did 35 Mbits/sec down, with little fluctuation), the iMac is now down to around 17 to 18 Mbits/sec (with much more fluctuation).

And I suspect it will keep going down ... so, whatever this change does, it is temporary! 😟

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Answer 4

John Galt

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Jan 29, 2012 10:34 PM in response to szhosain

I am sorry to hear this did not work. I reviewed the other thread, and it certainly gives the impression of a common problem, which is odd since my 21" iMac does not appear to be affected by its orientation.

I assume this is not something that occurred to you recently?

Is it possible to use a 5 GHz network? It wasn't apparent from a cursory search of the D-Link 655's specifications. The 5 GHz band may help, or it may make things worse.

I know you can't turn the iMac around, but is it possible to relocate the router?

Sorry I can't offer much more help with this. As you noted the best solution is wired Ethernet. Portables can overcome orientation issues easily enough, but desktops should be wired if practicable. A wired network connection eliminates so many potential problems.

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Answer 5

422

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Jun 13, 2012 10:22 AM in response to szhosain

I've had the same problem (slow wifi connection) for months with my 2010 27" iMac. Tried pretty much every suggestion out there until I saw this post - never imagined the proximity to the wireless router could be the problem since my other devices (iPhone, iPad, Windows7 HP laptop) in the same room never had any problems. When I moved the iMac over to the livingroom where my router is located, the connection speed went to normal (~20Mb/sec). When I moved it back to my other room (same floor but walls in between), the speed dropped to ~2Mb/sec. Again, my other devices in this same room gets the normal (20Mb/sec) speed, it's only the iMac drastically dropping the speed when moved farther away from the router.

To make the long story short, I gave up and got myself a wifi range extender ($60, Netgear) and placed it in the same room as the iMac, problem gone.

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Answer 6

Apr 26, 2013 6:43 AM in response to szhosain

Some days ago, I purchased an iMac 27", those so slim, I love it, but I have 2 problems:

- I used the migration assistant from my MacBook Pro to transfer data and apps (as iWeb I'm using it and its not comming with new Macs) but my mistake was to copy the user account of my MacBook Pro to my new iMac, then i deleted the account from the settings and unmarking the option of save delete, to completeley delete all the data related to that account, and I' think after doing this, my wi-fi connection become to be sooooo slow, but the wired internet connection with RJ45 cable works completely fine, at maximum speed.

- I tried everything I've seen in google to fix the slow wifi in a Mac, using the ipfw commands in terminal, changing the MTU to manual with a LOT of cases (1453, 1470, etc), upgrading my Wifi access point firmware (D-Link DWL-G700AP), activating DHCP in the access point, changing security of the access point from WEB to WPA2-PSK, changing the channel from 6 to 1 or 11 of my wifi access point, deactivating firewall in the iMac, moving away the wifi access point (actually is at 4cm behind the imac) and anything fixed the slow wifi connection, when my old PC HP TouchSmart 600 works pretty good with wifi, at maximum speed.

So I decided to format the new iMac and start from zero thinking the problem was to transfer the system account from my MacBook Pro to the new iMac, and now, its no way to download the mountain lion .dmg from the appstore and create a usb, so I have to use my SLOW coneccion (4mb) to download the entire OS, that way I have to download from the cmd + R to download it, so I need to be more than 5 hours WITHOUT using my iMac, and the worst thing is that i could not access to the disk utility to format the HDD, so when I returned to the re-installed mountain lion, I saw everything was the same, same screensaver, same data in my disk, same apps...

So, how its supposed Apple let us do a completeley format and reinstall mountain lion from zero without a dmg of our OS?

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Answer 7

szhosain Author

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Apr 26, 2013 7:39 PM in response to SamxFisher

I don't know how to answer the specific question you are asking about - in regard to the format and re-install.

With regard to the slow WiFi we were experiencing, I essentially gave up. As far as I an concerned, it is pretty clear that the iMac has a fundamental bug of some sort in its WiFi. Whether it is hardware or software, I cannot tell you.

When we moved the iMac back to our family room, in close proximity to the WiFi router (about 6 feet away!), it would still experience poor performance - fluctuating up and down, without ever getting really maximum throughput. Even though everything else (my Lenovo, a Sony Blu-Ray player about 12 feet away, my son's MacBook Pro, my wife's MacBook Pro, etc.) worked very well with both the WiFi routers.

So, in frustration, I gave up. 😠 😟 I connected an Ethernet cable from the iMac to the D-Link and shut down the WiFi on the iMac.

The wired connection, of course, works perfectly well! 🙂

In summary, I would say that the iMac we have has a serious flaw in its WiFi implementation - I am not sure whether it is HW or SW. My belief (unsubstantiated, but reasonably likely) is that it is a HW flaw - must have something to do with the antenna location behind the logo plastic. This simply must not be a good spot for the WiFi hardware/antenna location period.

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Answer 8

John Galt

Level 10

141,150 points

Apr 26, 2013 8:55 PM in response to szhosain

In the fifteen months since you first asked about this, I have heard of at least one other problem in which poor wireless performance was determined to be interference between Wi-Fi and the iMac's Bluetooth wireless. In that case the cause was determined to be the wireless router was too close to the iMac.

On rare occasions, the uncertainty of environmental variables affecting wireless networking leads to a counterintuitive solution.

Given your iMac's proximity to the router it makes sense to use Ethernet, but it is unlikely to be a design flaw.

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Answer 9

szhosain Author

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Apr 26, 2013 9:38 PM in response to John Galt

Thanks, John. I hear your reasoning, but I am not convinced, of course! 😉

FWIW, effectively, I tried different distances from both routers too ...

The D-Link DIR-655 is now 6 feet away with a wired connection. Using WiFi, we had tried between 6 to 12 feet, and the performance was bas as described - with 20 feet (in our dining/living room), it was essentially unusable at 2 to 6 Mbits/sec when the iMac faced away from it. With 6 feet WiFi, it still is not as fast as the laptop connections to it. When we sit in our family room sofa, the MacBooks and Leno are about 3 feet from it and work very well!

FWIW, we could easily change the performance by simply rotating the iMac physically without doing anything else! When the back of the iMac was turned toward the router, the performance increased (quite dramatically, but not as good as wired Ethernet, and fluctuating) and turning it away, it decreased (again quite dramatically).

With the Netgear router (upstairs in our house), the distance was about 30 and 45 feet (or so) in the two locations we had tried for the iMac. With that router too, turning the iMac to have the back towards it would cause the performance to improve - again not to the best possible with the MacBooks and Lenovo.

With both routers, the WiFi performance is not a limitation for all our other equipment (including multiple Apple products, my Lenovo, etc.), and the speeds were maxed to the Comcast cable speeds limits (which is now 55 MBits/sec since they increased performance recently).

Indeed, we use all the other computers with WiFi and do not have any problems anywhere in our house with either router.

Now, having said all that, we have never tried to use the iMac with just the WiFi on (i.e., after disabling Bluetooth). This would be an interesting test for sure - just for curiosity's sake, I will try to see how that does! 🙂 But, I need to go find and drag out a wired keyboard though, because the iMac we have has the wireless keyboard, so typing commands might be tough with the Bluetooth turned off. 😉

Recently, I also bought a new Asus 802.11AC router ... it is about 35 feet away upstairs. My Lenovo and a Kindle Fire HD connect beautifully with it - both 2.4 and 5 GHz work very well (of course, my laptop is still 802.11n ... I forget what the Kindle has), so I will also test the iMac with that too if I get a chance.

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Answer 10

Aug 31, 2013 7:18 AM in response to SamxFisher

Some months ago, I changed my wifi access point for a newer compatible with wifi 802.11n, and problem has gone, now I can use my iMac at full speed in wifi.

So I admit, the problem IS NOT the iMac, is the wifi router or wifi access point.

If u want to solve the problem, you'll need to purchase a new router / wifi access point with 802.11n compatibility.

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Answer 11

szhosain Author

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Sep 1, 2013 1:12 AM in response to SamxFisher

Hmmm ... as I had mentioned in my original post, I had tried the iMac with a brand-new Netgear WNDR4000 too ... that has 802.11n. With the same poor results. The Lenovo and MacBook Pro worked fine, but the iMac did not (on WiFi).

We also recently bought my wife a new MacBook pro and it also connected just fine with the DIR-655.

As it happens, last week, I had to replace the D-Link DIR-655 (because it was dropped and one of the antenna coverings broke) with a D-Link DIR-868L. This is a brand-new high-performance 802.11ac router and should also have exception 802.11n capabilities. Will do some testing with the iMac and see how it goes - so far, two Lenovo laptops and both MacBook Pro's are working very well with it!

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Answer 12

szhosain Author

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Sep 1, 2013 1:17 AM in response to szhosain

Forgot to mention that Comcast had increased the speeds in our area ... we are getting 55+ Mbits/sec down and 11+ Mbits/second up on Internet access (as reported by speedtest.net).

This is achieved on both Lenovo laptops and both MacBook Pro laptops - just need to see what the iMac does with the new 802.11ac router I now have.

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