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

Aug 23, 2012 6:17 PM in response to henrijacobs

I had same exact problem, every times I have to restart or shutdown my macbook, I can't turn on wireless on my laptop (wireless icon seem "on" on menubar, but can't find wifi signal) and I had tried most solution this forum offer to no avail.


This morning I think I've found a work around for this:


Before restart or shutdown turn bluetooth on, then if wireless will be fine

I've tried this several times, if I turn my bluetooth off before restart, wireless problem show up, but if I turn bluetooth on before restart then wireless will be fine


Hope this help.

Aug 23, 2012 6:31 PM in response to henrijacobs

Update from me. This only happens when my iMac (summer 2011) goes to sleep. If that happens and I loose Internet access, if I renew the DHCP lease and then go into the Internet connection tool and click "next" the whole way through, it will reestablish the connection without any problem.


While this has decreased the impact of the problem, it is still something that Apple needs to address.

Aug 23, 2012 11:54 PM in response to henrijacobs

Just to add my name to the list of many people on many threads about this problem in Mountain Lion...


My wifi disconnects from the internet, without feedback from the wifi icon. It stays connected for a few minutes at a time. If I stream a YouTube video, it disconnects within 10 or 20 seconds.


No solutions have worked. I've tried every reboot, reset, remove-then-re-add suggestion under the sun. Like virtually everyone on these threads, none of these have worked. The latest update — 10.8.1, has not included a fix.


• Macbook Pro 2.53 GHz Core 2 Duo

• D-Link DIR-615 router

Aug 25, 2012 10:54 AM in response to henrijacobs

Each time I wake my MacBook Pro from sleep, it fails to make a WiFi connection. Approaching the WiFi icon in the menu-bar causes the pointer to turn into the spinning beachball. I can open System Preferences, but trying to open the Network panel again causes the cursor to turn into the spinning beachball. The only way out of this, it seems, is to Restart (and this often first involves force quitting applications).

Aug 27, 2012 7:48 AM in response to digitalwhite

I tried the solution on osxdaily and it did 0 to solve the connection problem. First I updated from Lion and experienced the dropped connections even after trying the MTU trick. I decided to perform a clean fresh install on my imac and THAT didn't help either.


I don't understand why they don't simply revert to the stack they used in Lion which worked perfectly they didn't need to "upgrade" the networking at all.


I even stopped my imac from sleeping but it still randomly disconnects on it's own.


I may just switch back to Lion, this doesn't seem like a major OS upgrade anyway.

Aug 28, 2012 9:29 AM in response to henrijacobs

Joining the ranks of frustrated wifi users. I updated to ML this weekend thinking that a few weeks down the line, the rough spots would be fixed. I used to enjoy a mostly consistent wifi connection, all the way up to the upgrade. Now I've installed, I'm getting massive wifi dropouts that bring the web to a crawl reminiscent of those good old days of 'dial up' I use iStat menus to see my download and upload speeds. Youtube videos provide my general bench mark, I can see that I can be chugging down data at around 250kb/s then suddenly drop to 40kb/s then back up, then back down. My old normal speed was around 250kb/s, which was acceptable considering my Broadband and distance from exchange.


I've tried a few suggested fixes, the issue is still there.


An official Apple update is something I hope will resolve the issue.

Aug 29, 2012 9:55 AM in response to henrijacobs

My iPad works fine

My iphone 4's all work fine ( I have 3 of them)

My iphone 3 works fine

My sky, my Blu ray, my 2 apple tv's all connect fine


My iMac since loading update to mountain lion looses Internet connection so often it is infuriating.


I have replaced all wiring and installed a new router - the issue is the software on the mac!


How do I revert to mountain Lion?

Aug 30, 2012 2:03 PM in response to henrijacobs

Add me to the list as well. Had no issues whatsoever with Lion, but since upgrading to ML on my Macbook Pro I get constant disconnects from wifi. I've tried all the tips I've read online after Googling about this issue but nothing works for very long. I connect to Airport Extreme's at both home and work, both on the latest firmware. iPad and iPhone work fine. Mac Mini at home that is still on Lion works fine. Just the one system I upgraded to Mountain Lion having this issue.


Apple, get off your butts and fix this!


--Jim

Aug 30, 2012 2:03 PM in response to David Neale1

Mac Pro 2011, former Leopard 10.6.8, Mountain Lion upgraded


It works for WiFi, but as I prefer ethernet (since its a desktop), as soon as you plugin the ethernet cable, the internet is gone again which means you have to repeat the process in order to get the internet back to work.


Too bad as I need to use my computer next week on a large fair where most likely there is only ethernet based (fast) internet for large uploads available. I hope Apple can fix this soon indeed.


Good luck everyone

Sep 3, 2012 6:21 AM in response to henrijacobs

I can't believe it.

First of all : you think your 2000$ imac is damaged, then you try your other gadgets...

My iPhone works fine, my iPad2 works fine, my iMac27 goes out of track!

This is ridiculous.

Apple: what's going on?

How much time do you need to solve this?

How many posts do you need to solve this?

This is the Tim Cook's quality control era?

Steve, we miss you !

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Mountain lion wifi problems

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