Agnieszka G
Level 1 (12 points)
Desktops

Q: iMac won't connect to wifi

I have a 2011 iMac 27 3.1 ghz with i5. I am running El Capitan 10.11.6 which is the most up to date version.

 

I Never had an issue with the wireless connection before. Recently my iMac had to go into genius bar due to graphics card failing. Costing nearly 400GBP to fix, I was relieved to finally get it home, only to find it now won't connect to our wifi network. I connected the iMac to the router with a cable but it is super slow. I have spent a few nights now on these forums trying to find a fix, but most similar issues are from a few years ago and the steps don't seem to be do-able on my computer. I am not hugely technical, but I went through a similar thread of 14 pages which had some 'fixes' but none of them worked. This is my last chance saloon before having to carry the huge computer back into Apple store again and getting charged lots of money

iMac, OS X El Capitan (10.11.6)

Posted on Sep 8, 2016 4:12 AM

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Agnieszka G

Q: iMac won't connect to wifi

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  • by tygb ,

    tygb tygb Sep 8, 2016 5:10 AM in response to Agnieszka G
    Level 2 (204 points)
    Mac OS X
    Sep 8, 2016 5:10 AM in response to Agnieszka G

    Hello !

    Please hold option key and click on wi fi icon

    ( a) open wireless diagnostics , take cursor to top left  menu bar select open external tool.

     

      Screen Shot 2016-09-08 at 5.32.41 PM.png

     

    Click on network diagnostics

    Screen Shot 2016-09-08 at 5.32.56 PM.png

    select location

    Screen Shot 2016-09-08 at 5.33.17 PM.png

    Then , click on continue network diagnostics window will appear

    Screen Shot 2016-09-08 at 5.33.29 PM.png

    Again click on continue and follow the steps finally click on quit .

     

    All network status must appear as green .

     

    Suggested  article : OS X El Capitan: Use Network Diagnostics

     

    Thanks !

  • by Agnieszka G,

    Agnieszka G Agnieszka G Sep 8, 2016 2:25 PM in response to tygb
    Level 1 (12 points)
    Desktops
    Sep 8, 2016 2:25 PM in response to tygb

    Thanks for your reply. Unfortunately this didn't work either.

     

    I should also mention, we have 3 iPhones, a Macbook Pro, a Samsung Galaxy S5 and an iPad all connected to the network with no issues. We have unto 16 devices allowed on our network.

     

    When I use the 'assist me' tool on the bottom of the 'open network preferences' it says the router might be too far away, but it is right next to the computer and the other devices can even pick up the wifi from outside our building. The above attempt generated a diagnostics report which is lots of letters and numbers and means nothing to me.

  • by tygb ,

    tygb tygb Sep 9, 2016 4:34 AM in response to Agnieszka G
    Level 2 (204 points)
    Mac OS X
    Sep 9, 2016 4:34 AM in response to Agnieszka G

    Can you give  some details what settings are there on DNS , wifi security- WPA2 personal AES , etc .in network .

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

  • by Agnieszka G,

    Agnieszka G Agnieszka G Sep 9, 2016 3:40 PM in response to tygb
    Level 1 (12 points)
    Desktops
    Sep 9, 2016 3:40 PM in response to tygb

    Ive used the wireless diagnostic tool quite bit and it doesn't seem to tell me anything except to move closer to the router - which it is next to so can't get much closer!

     

    On the DNS tab, under 'DNS servers' it is blank, and under 'search domains' it is also blank. I checked on my Macbook Pro and added these settings on my iMac but it didn't do anything. On the DCP/IP tab, the 'IPv4 address' was blank aswell as the 'subnet mask' and 'router'. It has 'configure IPv4' as 'Using DHCP' which I tired changing to 'Using DHCP  with manual address' and tried to add the IPv4 as off of my Macbook Pro. That didn't work. I changed 'configure IPv4' to 'Manually' and entered all of the IPv4, Subnet mask and router, again, nothing. Ive tried deleting the wifi and immediately adding it back onto the lefthand menu, still nothing. Security wise it is WPA2 personal. I'm not sure what 'AES' is??

  • by Tesserax,

    Tesserax Tesserax Sep 9, 2016 4:29 PM in response to Agnieszka G
    Level 9 (54,040 points)
    Wireless
    Sep 9, 2016 4:29 PM in response to Agnieszka G

    The blank IP addresses indicate, for some reason or another, your iMac is unable to find a DHCP server when connected by wireless. However, you also mentioned that even when connected by Ethernet it is slow. Both of these would indicate a potential hardware issue still exists with your iMac. Whether or not, it was introduced when you had the graphics issue resolved is unknown at this point.

     

    I am going to assume that Wi-Fi is your preferred network connection so we are going to try some troubleshooting along this line.

     

    Try the following on your Mac in order, until (hopefully) resolved:

     

    1. Create a New User Account
      • System Preferences > Accounts
      • Click "+" to add a new account.
      • Log off, and then, log back on with the new user account.
      • Try connecting to your Wi-Fi network.
      • If this resolves the problem, there may be something amiss with your current profile and will require further troubleshooting.
      • If this does not resolve the problem, go ahead and log back into your normal account and go on to the next 3 steps.
    2. Delete AirPort Keychain Entries
      • Launch the "Keychain Access" application located in Applications/Utilities.
      • In the windows on the left side: Select login for Keychains and "Passwords" for Category.
      • Click on the "Kind" filter at the top, and look for any "AirPort network password" entries...and delete them.
      • Close Keychain Access.
    3. Delete Preferred Network(s)
      • System Preferences > Network > Wi-Fi > Advanced > Wi-Fi tab
      • Delete all entries under "Preferred Networks."
      • Click on OK.
    4. Add Preferred Network(s)
      • System Preferences > Network > Wi-Fi > Advanced > Wi-Fi tab
      • Add the preferred network(s) using the "+" button.
      • Click on OK.
      • Restart or log out, and then, back in.
        • If it works, then you are done.
        • If not, go on to the next step.
    5. Move System Configuration Files
      •   In Finder, go to /Macintosh HD/Library/Preferences/
      • Move (not copy) the entire SystemConfiguration folder to the OS X desktop.
      • Restart the computer.
      • Verify that you have connectivity.