Mountain lion wifi problems

I have just installed mountain lion.

All went good, but now i have à problem with wifi.


My connection is ok, i get an ip adress, but i cant get On internet.


Safari says it has no internet connection.


When i connect on ethernet i have internet.


Do anyone know what The problem is?

MacBook Pro, OS X Mountain Lion

Posted on Jul 25, 2012 2:13 PM

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Question marked as Top-ranking reply

Posted on Aug 4, 2012 9:28 AM

I have the same exact issue. 😟

Please help. I tried everything. I found these but to no avail. still cant connect.


Fix #1: Add a New Network Location & Renew DHCP

This may work best for those who upgraded from a previous version of OS X to Mountain Lion but if you’re having the wifi drop issue go ahead and do it anyway because it is consistently successful with addressing wireless issues:

  • Open System Preferences from the  Apple menu and choose “Network”
  • Pull down the “Location” menu and choose “Edit Locations…”
  • Click the [+] button to add a new location, name it whatever you want then click Done
  • Back at the “Network” screen, click the “Network Name” menu and join the wireless network

Your wireless connection may now be active and working fine, but renew the DHCP lease anyway:

  • From the Network panel, click on the “Advanced” button in the lower right corner, then click the “TCP/IP” tab
  • Make sure “Configure IPv4:” is set to “Using DHCP” and then click the “Renew DHCP Lease” button, click “Apply” when prompted
  • The appropriate DHCP settings should be renewed from the connected router, click “OK” and exit out of System Prefs

User uploaded fileThe network location and DHCP renewal tip resolved similar wifi problems in Lion, and it seems to work in Mountain Lion too for many users.

Fix #2: Change MTU Size to Prevent Dropped Connections

This is a bit geeky but bare with us: MTU stands for Maximum Transmission Unit and controls the largest packet size allowed for transmission over the network. If this setting is greater than network capacity, the computer will experience packet loss and dropped connections. The default setting of 1500 is somewhat aggressive and some networks reject packets of that size, but it turns out that 1453 is just small enough to maintain a consistent connection with most networks but just large enough to not cause any slowdowns, it’s the magic number and an old cisco networking secret.

  • Open System Preferences from the  Apple menu and select “Network”
  • Click the “Advanced” button in the lower corner, followed by the “Hardware” tab
  • Pull down the “Configure” menu and set to “Manually”
  • Change “MTU” to “Custom” and set the field to “1453″
  • User uploaded file
  • Click “OK” and close out of Network preferences

Be sure you’re joined on a wireless network, close out of System Preferences, and enjoy the internet as usual.

371 replies

Feb 7, 2013 12:15 AM in response to Rustproofbug

After 4 days of Apple Care support and an overnight stay in Apple tech hospital, it turns out my Macbook Pro with Mountain Lion OS (10.8.2) had difficultly communicating with my Netgear CG3100D. Solution: Apple provided me with an AirPort Express and I turned the NAT and Wifi off on my Netgear modem/router. Note: had to also turn Bridge mode off on the Airport Express.


Upshot is that Apple products are not always compatible with other products and vice versa.

Feb 7, 2013 7:38 AM in response to Bob Allison

That seems to be the solution to one of the problems.. it seems to me there are 2 problems being discussed in this thread.... (correct me if im wrong)


Problem 1: wifi not connecting when waking up from sleep etc (solution you mention above)


Problem 2 (the one i'm having): wifi shows as connected but there are constant 'invisible' drop outs in the connection - havent found a solution to this that works for me, though Jacofalls post is interesting in that I'm also on a netgear product.

Feb 7, 2013 8:04 AM in response to johnboyuk

I guess that's part of what I am saying.

The original problem 1 was answered. But others just this week are struggling with it because they didn't see the answer in what are now 240 replys.

imho problem 2 should have been a new thread - 2 problems in this thread is enough.

I'm just asking that people be careful to make new threads and not add anything else to this one.

Feb 8, 2013 9:04 AM in response to johnboyuk

johnboyuk wrote:


That seems to be the solution to one of the problems.. it seems to me there are 2 problems being discussed in this thread.... (correct me if im wrong)


Problem 1: wifi not connecting when waking up from sleep etc (solution you mention above)


Problem 2 (the one i'm having): wifi shows as connected but there are constant 'invisible' drop outs in the connection - havent found a solution to this that works for me, though Jacofalls post is interesting in that I'm also on a netgear product.

1 question for now, have you been able to try with a different router?


OK, 2 questions,


I have had (limited) success by changing security settings, it's a bit random but switching from WPA2 to WPA fixed it in one location, unfortunately the opposite has also worked so maybe it was just the change, not what to.

Feb 9, 2013 5:02 PM in response to Csound1

You are right, this discussion is about 2 different problems. Problem 1 is just annoying, problem 2 (your and my problem) is a fundamental one. I tried everything, including a different router (though I must admit it is the same brand, one version higher) but nothing works: wifi drops the connection at irregular intervals, the only remedy is to stop and restart wifi, and then hope it will stick, which it doesn't. My solution was to reconnect the good old ethernet cable, but that is not a solution for the problem. Many 'victims' have complained during the last year and a half or so, but Apple never responded.

This problem showed up after the switch from Lion to Leopard. IMHO the new firmware for the Airport Extreme card is the culprit. (Mountain) Leopard introduced a new version Atheros 9380: 4.0.etc for this card, and wifi is bad ever since. But only on Macs using this wifi card, like my mid 2011 iMac, the rest of the world connects happily to the router with no connection drops at all.

I don't think security settings have anything to do with this, but who knows ...

And BTW: those geniuses at the Apple Store here in Amsterdam never heard about this problem. Does that mean we are doing something wrong? Don't think so.

Feb 10, 2013 9:24 PM in response to neale121

@neale121

Thans, those steps did it for me. I think creating a new "Location" in the network preferences is basically a way to start clean and fresh with a bunch of under the hood settings that get poisoned especially if you migrated from an older system. Cleans out the cruft, I suppose.

Same steps and more are here:

http://osxdaily.com/2012/08/02/fix-os-x-mountain-lion-wireless-connection-proble ms/


PS: To elaborate, I was having lots of issues with my retina MacBook Pro WiFi, on various WiFi networks - this is definitely my machine, not the various networks it sometimes doesn't connect to or doesn't work with. I did not yet delete all WiFi passwords, but will do that if the new location fix above isn't enough.

I also can't download without interruptios - tried about 5 times last night to download the full iOS 6.1 update through iTunes from Apple's severs, at 1MB/s. Never finished, and iTunes then starts over, so in effect I am unable to use iTunes to download the update. Ended up downloading the IPSW with a download manager which of course worked fine.

Feb 12, 2013 7:37 AM in response to henrijacobs

I started having the wifi problems under Snow Leopard, was about ready to upgrade to Mountain Lion anyway, and thought the upgrade might solve the problems - strong networks in the house appearing and disappearing, connection timeouts when trying to join, etc.


The upgrade didn't help; I had the same problems.

My setup is an Asus RT-N56U (excellent, fast router) with Network1 on 2.4gHz, and Network2 on 5gHz. I also have Network3, a Linksys WRT160Nv3 running DD-WRT set up as a repeater bridge, linked to Network1.

Connecting to any network had problems, but it was a little better connecting to Network2, so I thought there might be a problem with the others.


I downloaded a new copy of the firmware for the WRT160N and went through the process of setting up the repeater bridge. When done, all networks worked fine, better than ever, fast, no dropouts - fixed! Just tinkering, I enabled UPnP service on the Linksys WRT160N.


Bad move. All problems returned. I just went back in and disabled UPnP on the Linksys WRT160N and now everything is fine. It's been a couple of hours, and no problems, just fast reliable wifi. Hoping this might help others solve the maddening problems. Good luck!

Feb 12, 2013 11:43 AM in response to PhilMilo

I think i have fixed the problem (at least for me) and i have not seen this mentioned (i could not read the 17 pages of threads but read 11 of them)


i also spent 4-5 days on phone with mac "senior expert" two of them and a trip to apple store and no help


i also erased wifi and put it number 1 or number 2 before ethernet

did an SMC reset

did clean install

updated firmware on airport

erased system comfig .plist files

i also erased saved locations

erased keychain passwords

restarted a lot


finally finally i added two DNS server addresses in my system preferences>network>advanced>DNS


i used the plus icon to add 8.8.8.8 and 8.8.4.4 (google DNS servers) and it has worked

on my router on starbucks at work at school

3 hrs now....

Feb 15, 2013 8:54 AM in response to PhilMilo

Problems returned. Maddening. Tried the following yesterday and everything is working great so far (>24hrs), including wake from sleep automatically rejoining the network and speedy and reliable performance.


Just to make it as clean as possible, I went into the System Preferences->Network->WiFi->advanced ->wifi, removed all references to the problematic networks, then went to Keychain Access, Login Passwords and System Passwords and deleted any references to the problematic networks.

Then did the following procedure I found at MacRumors http://http://forums.macrumors.com/showthread.php?t=1207455 (scroll down a ways)


********************************

Remove the network and add it manually

I just removed the network for the Preferred network list (Sys Pref->Network->Wifi->advanced ->wifi) , then added it manually (with the + sign under the list) with a wrong password and tried to connect, the password window showed up and when I entered the correct password, it worked perfectly, hope this helps.

*******************************

I consider kkhair a networking genius :-)

Hope this helps. Will report if any failures return.

Feb 20, 2013 3:59 PM in response to PhilMilo

I could have told you so. A couple of hours is not enough to start cheering. I worked on this problem for over a year, and finally convinced AppleCare there is something fundamentally wrong with WiFi on Mountain Lion machines like my mid 2011 iMac. I transported the iMac to the Apple Store here in Amsterdam, where they are going to replace the WiFi-card. The geniuses there promised me everything will be ok after this operation, but denied they heard of this problem before. Tomorrow I can pick up the machine. Will keep you posted.

Feb 23, 2013 3:44 AM in response to henrijacobs

Hi, I'm also having the same problem on an iMac 2011 and tried almost every suggested solution.


However, I have found out that when I disable the Time Machine backup to my Time Capsule (2009 I believe) and back up to a USB drive instead, the wifi disconnections seem to not occur at all! They haven't since over a week now. As soon as I choose TC as the TM drive again, the connection fails regularly as before.


No wifi problems for MBA 2010 and iMac 2009 at all although also backing up to the same TC.


Does this happen for anyone else? Do you think replacing the TC would help?

Feb 24, 2013 7:57 AM in response to henrijacobs

add another..

just bought $2800 iMac and put the old one upstairs on Wifi

new 27 arrived migrated everything over.. and loved it (still do) - connected via ethernet cable

running ML


Lion guy upstairs does the DROP wifi often!! realized as trying to find printer etc. not sure if ML and Lion not playing well together but looks like more of an issue as i am reading here. Kids were planning to use the 2008 imac 24 for papers etc in pages upstairs and print to printer downstairs - I have had no problem sharing this printer in past with this very iMac and MBP - so should be no problem. Since it finds and then drops printer too i am thinking this is all related as a WIFI issue...


anything from apple on this yet! VERY frustrating as I and using Airport Extreme and all apple products


now we have

iMac 2012 Dec 27" 32gb ram i7

MBP 2010

imac 2008

2 ipads

2 iphones

2 ipod touch

MB air - original


i mean we are total apple.. so im hating this after I always slam the PC friends.. I have heard ML is the VISTA of mac.. man o man.. cmon apple!!

Feb 24, 2013 10:15 AM in response to CT

I am referring to the wifi drop problem in mountain lion (ML) I too am experiencing this issue and tried the original 'fixes' with no help. Don't know if you have read the original post to put in context.


some info extraneous to problem, but included in case makes a difference -- i.e. iMac i am using via wifi is running LION not Mountain Lion. As you may be able to tell by the number of posts this is an issue for a number of folks re: wifi drops.


hoping apple addresses problem soon and looking here for any other solutions to try --

Feb 24, 2013 1:50 PM in response to jdcarpe3

I fixed my issue with the wireless drops. It turns out that my access point had a beacon period set to 50 Kms. I set the beacon period to 100 Kms and my drops have stopped.


Here are some details regarding what the beacon period is -- http://www.cisco.com/en/US/docs/wireless/access_point/12.2_11_JA/command/referen ce/cr11main.html#wp2448729.


"Clients normally wake up each time a beacon is sent to check for pending packets. Longer beacon periods let the client sleep longer and preserve power. Shorter beacon periods reduce the delay in receiving packets."


This is a more advanced change on your wireless access point/router, but it may be worth trying all the other suggested changes have failed to provide improvement.

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Mountain lion wifi problems

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