problems with wifi, Safari and Mountain Lion

If you’ve upgraded to Mountain Lion and traded swift wifi and fast Safari for a flakey internet connection and sluggish browser, you are not alone. Widespread reports of problems with wifi, Safari and Mountain Lion have been mounting ever since July 25th. However, unlike the lengthy debacle with similar wifi problems experienced after the Lion upgrade last year, a lot of users are finding their problems can be solved by using one or more of the tips below.

1. Create a new location and renew the DHCP lease
OS X Daily have a step-by-step procedure here

that is proving hugely successful. Don’t forget to follow their second step about changing the MTU value while you’re at it.

2. Reset default system preferences
If that didn’t do it for you, it’s time to roll up your sleeves and enter Terminal! Open the from


and paste this command

rm ~/Library/Preferences/

then press ‘return’.

You will need to restart your mac to see if this has had any beneficial effect, so do that now.

3. Do PRAM & SMC resets
If you’re still suffering problems, it’s time for a couple of system resets. To do the SMC reset you will need to see what kind of mac you have, as the procedure is different for some models. Take a look here and follow the instructions for your model.

Before powering up after the SMC reset, also take the trouble to do a PRAM reset. To do that:

i. Ensure the machine is powered off.

ii. Locate the following keys on your keyboard in preparation for Step 4:

‘command’ – ‘option’ – ‘P’ – ‘R’

iii. Press the ‘power on’ button.

iv. Immediately – and before the grey screen appears – hold down ‘command-option-P-R’ all together.

v. Keep them held down until you’ve heard the start-up chime twice. After you release them you should hear it again, and hopefully your Mac will boot up without wifi/Safari issues.

4. Check Wifi connection
And if that doesn’t work? Time to check your wifi connection. See how strong your signal-to-noise ratio is. You need something in the order of 25 or higher. To find out whether you signal is strong enough, hold down the ‘option’ key and click on the wifi icon in the menu bar. Choose Open Wifi Diagnostics from the menu.

When you see the welcome screen, ignore the ‘Continue’ button and instead press ‘command-N’ on your keyboard.

Click wifi scan in the task bar and scroll to the right where you will see two numbers, ‘signal’ and ‘noise’. Ignore the minus ‘-‘ signs, and subtract the signal number from the ‘noise’ number. Anything over 25 is a good enough signal, below that and the signal is too weak for a reliable connection. Over 40 is excellent (in the example below, you can see the SNR is 34, a pretty good signal for a home router located on the next floor).

If your SNR is lower than 25 you need to either move the computer closer to the router or find a better connection. If the ‘Noise’ shows a very low figure (equals more noise), you can try changing the channel on your router. Look at the other routers in the list and if they are using the same channel as yours, switch your router to something else between 1 and 11.

5. Reinstall OS X
If all else fails…some users are reporting that simply reinstalling OS X is solving the problem for them. Reinstalling doesn’t touch your Apps or user data, but its always wise to make sure you have a backup before undertaking such an operation.

To reinstall, restart the computer while also holding down ‘command-R’ on the keyboard. From the Utilities window that opens up, choose ‘Reinstall OS X’.

Still having problems? Let us know in the comments below.


featured picture: Internet by ~vagraine

About philastokes

Freelance Writer, Developer and Technical Communicator. Explaining the unexplainable with images, video and text. Scripting anything imaginable in Applescript, Bash, C, Objective C, Cocoa, Python and Xcode.

Posted on August 7, 2012, in Mountain Lion, Safari 6.0, Wifi and tagged , , , , , , , , , , , , , , , , , , , , , , . Bookmark the permalink. 6 Comments.

  1. Hi all this info was really useful, i have done all the steps and it was definitely improving but wasn’t right still so i have tried to re-install mountsin lion and it says it will take 647 hours to complete the install!?! So this isn’t looking hopeful either?! Am i due a trip to an apple shop??

  2. I have a brand new mac mini 2012 fall release with 16GB and the best i7 quad core upgrade … safari is slower than my 2006 macbook with 2GB and a very early core2duo …. tried all the above and didnt make any difference – thing that helped most but hasnt solved it was to power down all the stuff on the network (ALL) and then reboot broadband/DSL and the router. Still V slow.

  3. Hi – as a soon-to-be iMac owner, are these issues likely to affect a brand-new iMac (minimum spec) pre-installed with Mountain Lion, as advertised? Do you think Apple use iMacs with previous OS X versions and then upgrade them before selling them, or do they do a new install before selling?

    • I think the wifi problems are more or less sorted out now.

      As for your second question, I’m not sure about that Andy. Perhaps any readers who works at an Apple store could weigh in here?

  4. Hello forum, the SMC and PRAM work for a while but it’s as if some old data is being loaded from somewhere causing a corruption and recurrence of the error minutes later.

  5. At last some light upon my problem. “2. Reset default system preferences” seems to have cured it. Thanks so much.

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