wifi connection failed. No IP address.

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wifi connection failed. No IP address.

Hi,

So after I upgraded to Yosemite I began to experience the error 'connection failed' when I try to connect to wifi or ethernet. All the other computers connect to the internet so I know it is nothing to do with my internet provider/router. I clean installed yosemite which fixed the issue temporaily then out of the blue, same error.

So, I had my desktop mac professionally looked at by an apple regarded technician who told me there is nothing wrong with the hardware, and, the wifi worked just fine for him as he could connect to the wifi in his office. When I took my desktop home, amazingly, my internet could connect via wifi again, strange. Then, out of the blue, same error, connection failed (I think this may have occurred after I accidentally unplugged the router one time).

After some self-diagnosis, I have discovered that I have no IP address information in the internet system preferences and so in order to resolve this I would need to renew the DHCP lease, however, whenever I click to 'renew lease', nothing happens!

Please help, Im lost!

Thanks

iMac, Mac OS X (10.7.5)

Posted on Feb 12, 2015 12:25 PM

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Answer 1

Feb 12, 2015 12:50 PM in response to Pointofview1

Check your router settings too. IP address show up there?

Disconnect & reconnect your modem. Unplug it for about 10 seconds. Plug it back in. Do the same for Apple’s routers. Wait for everything to reboot.

Run the diagnostic test:

System Preferences>Network

Click the Assist Me button.

In the next window that pops up, click the Diagnostic button & do the necessary.

Post the results.

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Answer 2

Pointofview1 Author

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Feb 28, 2015 12:16 PM in response to Baby-Boomer-USofA

Hi thank you for your reply, sorry for the slow response as I didn't see your message.

Ok, so what router settings go should I be looking for? All other devices in the house connect to the router so I imagine it has an ip.

When I run diagnostics I get the message -

"this computer was unable to join the WiFi network you selected. You may have entered an incorrect password or network name, chosen the wrong type of wireless security, or you may be out of range of the Base station."

I know the password I have entered is correct and the computer is close enough to the Base station and I selected my wifi network from the list..?

Kindest

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Answer 3

Mar 2, 2015 1:07 PM in response to Pointofview1

Ok, so what router settings go should I be looking for?

If you are using a 3rd party router, read the manual that came w/it for set up. Go over each setting especially the settings for the IP address.

If you are using one of Apple's routers, click on the Airport Utility icon & check the settings in the Internet & Network tabs.

Optional: Check the info you have in the Base Station, Disks & Wireless tabs.

If necessary you may need to reset the whole router and/or use a different channel, one that is rarely used. If you reset make sure you reconnect to the hardware one at a time.

After you are done run Network Diagnostics again after you restart your computer.

If you are still having problems, do the following:

Trash the following plist files by going to Macintosh HD>Library>Preferences>SystemConfiguration

com.apple.airport.preferences

preferences

NetworkInterfaces

Repair permissions and restart your computer. If the problem has been resolved, empty the trash. If not, you can return the plist files if you wish. New plist files will be recreated anyways.

Last resort: Get comfortable & check out this tread--> OSX Yosemite Wifi issues

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Answer 4

Pointofview1 Author

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Mar 17, 2015 1:13 PM in response to Baby-Boomer-USofA

Hey,

So, I finally got around to trying to fix my computer again, to find that the internet is now once again connecting! This is good news, but strange, because it shouldn't be happening as no settings to my computer or to the router have changed. I check my computer about once a week to see if it will connect, and this really is out of the blue.

This has happened twice before, where the computer suddenly will once again connect to the internet, but it never lasts long, only a week or so. Does this shed any light on the situation? I guess I ask because I know I will be facing the same problem soon enough..

Kindest

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Answer 5

Mar 17, 2015 1:29 PM in response to Pointofview1

Did you try all the suggestions I fonted "Mar 2, 2015?"

What to do when you can't connect to the Internet

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Answer 6

Pointofview1 Author

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Mar 22, 2015 4:22 AM in response to Baby-Boomer-USofA

Hey, so my I turned is off again 😟

I checked over the router set up manual to no avail. Regarding the settings for the router I am still unsure as to what it is I should be looking for and what to do with the knowledge? When I look at the router info, there is rather a lot of info.. I mean when you say the settings for the ip address,i really need more clarity please?

I have tried resetting the router. I don't know what it means to use a different channel?

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Answer 7

Pointofview1 Author

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Mar 22, 2015 4:35 AM in response to Pointofview1

If you are still having problems, do the following:

Trash the following plist files by going to Macintosh HD>Library>Preferences>SystemConfiguration

com.apple.airport.preferences

This takes me to a text edit file?

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Answer 8

Mar 22, 2015 11:03 AM in response to Pointofview1

Pointofview1 wrote:

Hey, so my I turned is off again 😟

I checked over the router set up manual to no avail. Regarding the settings for the router I am still unsure as to what it is I should be looking for and what to do with the knowledge? When I look at the router info, there is rather a lot of info.. I mean when you say the settings for the ip address,i really need more clarity please?

Then you need to call the router manufacturer, visit their customer support website and/or post in their forums. You need to determine if your router network settings are correct for your model Mac.

Regarding you IP address, you need to make sure it (router) matches the one in System Preferences>Network settings.

I was going by your previous statement: "I have discovered that I have no IP address information in the internet system preferences and so in order to resolve this I would need to renew the DHCP lease, however, whenever I click to 'renew lease', nothing happens!"

You can renew the DHCP lease in Apple Extreme. You will need to discuss this w/the manufacturer of your router.

I have tried resetting the router. I don't know what it means to use a different channel?

Regarding the channels, most if not all all routers have them. If you cannot locate the channel section/tab in your router again, contact the manufacturer.

The router instructions I provided previously was for Airport Extreme. You never mentioned if you are using an Apple or a 3rd party router.

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Answer 9

Pointofview1 Author

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Mar 22, 2015 1:24 PM in response to Baby-Boomer-USofA

I am using an ASUS router (RT-N66U Dark Knight). I thought the computer just picks up the ip address of the router so they would always match? My computer is't picking up an ip address.. its not picking up a connection..

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Answer 10

Mar 23, 2015 2:17 AM in response to Pointofview1

Did you trash those plist files I suggested?

The only other suggestion I have to offer is for you to download the

OS X Yosemite 10.10.2 Combo Update, repair permissions & restart your computer when done.

Read the "last resort" previous suggestion.

Sorry, I have no further suggestions to offer. You can always call Apple Tech support and/or take your iMac to your local AS or an AASP.

GOOD LUCK!!!!!

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