Macbook Internet Fast, iMac Internet Slow

I'm paying for 12 Mbps of DSL service. I moved into our home about three months ago and have been achieving 10-11 Mbps up to this point. About two weeks ago my Airport bars started to decline. SPEEDTEST.net is telling me today that I am only achieving 3-4 Mbps. I can't think of anything that I have done new in the past few weeks. Here's the kicker: My wife's Macbook sits approximately 6 feet away from my iMac and she has seen no drop off in speed. I can even have her laptop on my desk and her speed remains constant between 10-11 Mbps.

I am on Channel 6 (2.4 GHz)-----RSSI:-75------Transmit Rate:5

iStumbler shows WPA2---802.11n---Mode(Network)--Signal-28 Noise-17%

Any help would be greatly appreciated.

Try adding some DNS servers in there.

Its in settings. Been discussed before about slow internet.

DNS Servers:
192.168.0.1
205.171.2.65

Settings>Network>Advanced>Click the "+" option at bottom left>Add 208.67.222.222 and 208.67.220.220 and lastly 8.8.8.8>Click "OK"

Test the speed and if it doesn't speed up reboot and try again first.

Added the new servers and rebooted. 1 of 3 bars on my Airport indicator. Speedtest and Speakeasy registered over 11 Mbps. Two other speed test sites registered .8 Mbps. Went back to Speedtest and Speakeasy and they registered 2.73 and 1.30. So now the speed seems erratic, at best.

Dont know what to say

Try a wired (Eth) test and see what happens. Have you installed all updates? Apple site.

I hooked up to our wired connection and tested at speeds over 11 Mbps on two different testing sites. All updates are installed. Still receiving 2-3 Mbps via my Airport.

How far is your iMac from your Wifi Router? If the bars are lower it's probably decreasing the WiFi connection speed. Strange the Macbook though right on the same table gets full speed and bars. What iMac is this and version of OSX?

Just curious, is your internet AT&T UVerse?

As dtravis said, not sure what iMac + OSX versions you have, but seems like your issue is fairly common.

Users have had some success changing the wireless channel to one that's not in use in other local Wi-Fi networks. It seems to have mixed success, some permanent and some temporary. In cases where it's temporary or where there are multiple networks in the area, some people re-assign the channel from time-to-time. Others just disable and re-enable Wi-Fi under Network Preferences when the speed drops off.

There is also a common problem with Lion dropping connections entirely. Although it doesn't seem to be what you're experiencing, you can try this if the above doesn't work.

dtravis7: My iMac is probably 50 feet from the router. It's around a corner, down a hall and in a bedroom. (same floor) It's a 21" iMac, running Version 10.6.8.

Checco: How do I change the wireless channel? I've tried the disable/enable approach and it doesn't help, where at one time it used to. I would try it ten times and I'd finally get a strong signal. I'm not having any luck with that anymore.

I am downloading the update that you recommended above. At my current connection speed, I'm looking at an hour to complete it. I'll let you know if that helps at all.

Thanks for the suggestions.

Checco: The fix you recommended stated that I need the latest version of Mac OS X. I'm running 10.6.8 Do I need to download a version of 10.8 or can I just attempt the fix if my version is updated as much as it can be?

Apologies for the late reply. If you're referring to Wi-Fi Update V1.0, then it says that it's for iMac Late 2009 or Later running 10.7.3. What you should do is check whether there are updates that suit your system as is. What version iMac is it?

You need to change the Wi-Fi channel on your wireless router (iStumbler will tell you what channels are already in use around you).

I bought the latest upgrade from Apple. I'm now running 10.8.1 Ever since, my WiFi is speeding right along. I'm not sure why the change, but I'm not changing anything or complaining. In the past, it may run fast for a brief time and then go back to 2-3 Mbps. It's been hovering between 10-11 since yesterday afternoon when I made the upgrade.

Thanks for the help. Even if was just to get me to upgrade my software. Seems to have done the trick.

Clearly a bug in 10.6.8 then. Glad all is looking good, nice upgrade?