Mountain lion wifi problems

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

The 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″

• 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.

Interesting.

You can connected via Wi-Fi to your router but Safari reports you have no internet connection.

First lets see if your dns entries are good.

Open a terminal and try to ping apple like this:

ping www.apple.com

Let the ping command run a few times then hit control c to stop the pings.

Do the pings go through to www.apple.com or are you getting timeouts? Also, copy and paste the output from the terminal to this thread.

If you are getting pings to go through, can you run this command in terminal:

scutil -r www.apple.com

And then paste the output here of the above command.

Let's start here.

I should have been a little more clear. Ping cannot resolve a hostname like that.

the command should be:

ping www.apple.com (leave the http:// off of the hostname).

You could also try the following:

1. trash the system config PLISTS and reboot (note you will loose your iMac's network settings, so if you are using static entry's IP address, DNS, etc be sure to write them down before attempting this).

Open a terminal and do the following commands:

mkdir ~/Desktop/old_sys_configs

sudo cp -pR /Library/Preferences/SystemConfiguration/* ~/Desktop/old_sys_configs

cd /Library/Preferences/SystemConfiguration/

rm -rf *.plist

The above commands will save a copy of your current network settings to a folder on the Desktop. Reboot your iMac. When your Mac comes back, try to connect to your Ethernet network or Wi-Fi network and see what happens.

If you wanted to restore your old network configuration (since the files are on the desktop) all you would need to do is the following in terminal:

sudo cp -R ~/Desktop/old_sys_configs/* /Library/Preferences/SystemConfiguration/

And then reboot.

Check your router settings and see if you have Wireless QoS (WMM) enabled? If so, diable it. This fixed my problems, and had the benefit of speeding up my wifi in the process.

Bro, you must be having the same problem with many of the guys are facing. It's a known bug and waiting for apple to come out with solution. I suggest you stick to wired connection first. At least you are lucky. I am using iPad to reply you as I have the same problem as you. This also shows my internet wifi is good.

I had the WiFi issue too with my late 2010 iMac... had to change the router settings to WPA2 instead of WEP security. According to Apple Care, the WEP security is too old school for the new software. HTH.

I noticed today that AirPlay didn't work for more than 30 seconds on my 2007 MacBook Pro (trying it for the first time after installing ML). My 2010 Air, iPhone 4S, and iPad3 had no problem with AirPlay. I connected the 2007 MBP to my Airport Extreme with an Ethernet cable, and bingo the problem was immediately solved.

So I thought, oh, I must be part of this problem where a lot of people are having wi-fi connectivity issues with ML.

Called Apple, they had me boot in Safe Mode (hold down Shift while booting), which runs diagnostics and fixes like most of what runnuing Disk Utility would do, and now Airplay is fixed and working perfectly, just as it did before ML was installled.

tl;dr: solved wi-fi problem(s) by rebooting into Safe Mode and then rebooting.

(The next two steps would have been PRAM reset and then SAC reset.)

I changed my MTU to 1300 on the WiFi network and it solved my problem. Please try it and let us know if that solved it for you.

Go to System Preferences -> Network -> Advanced -> Hardware

check to Manually, MTU: 1300

4 hours later and problem returned. I feel burned.

The Apple specialist said, "Whenever there is an upgrade, 90% of user problems are because there was something wrong with their machines—it's not the OS update."

I took him at his words. What a fool I was.

I should have known when he told me he'd been doing his job for Apple for nine years. How many people in tech these days keep the same job at the same company for that long? It's just dumb.

I told him I'd in been in IT for 30 years; he just got more patronizing.

jfsiman, I will try your fix. Then PRAM and SAC reset.

Folks, just between us and the wall, I think it's an ML problem.

jfsim wrote:

>I changed my MTU to 1300 on the WiFi network and it solved my problem. Please try it and let us know if that solved it for you.

Nope, this didn't work. Nor did PRAM reset. Nor SAC reset. Nor making sure NONE of my other devices were set to any AirPlay Airport Express in my Loft.

Houston, we have a problem.

I'm calling Apple back.

Tried the same things with the same results - none. The fact that everyone else (non-upgraded) on the exact same network I am on is still fine and surfing smoothly while the only thing I did was to upgrade to 10.8 without adjusting anything else puts egg on my face as well as putting me in hot water with my employer as I cannot get things done! Angry and frustrated at Apple right now for releasing something that was NOT ready.

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17" MBP 2011, 2.4Ghz i7, 8GB Ram

I tried to press cmd+r at startup, and connectet to the wifi spot that way. Worked for me...