No wifi connection after installing Mountain Lion HELP!!

Having the same type issue on 2 of 3 macbooks:

- the newest macbook "early 2011 flavor" is connected to the same wifi network as 2 that are not and the wifi is working, but it is much slower than prior to the upgrade

- the older macbooks "2010 flavors" did work fine after the upgrade for a couple days and today wifi is no loger working although connected to the same wifi network are the one that is working.

We are using a Linksys G- router.

The only change on all 3 macbooks is the upgrade to mountain lion.

We have tried deleting the wifi, security keys, numerous reboots of all the equipment and same issue exists.

Any additional suggestions are appreciated.

I thought I did, but still had to download it all over again, and now... Same problem as before. Apple has sold us crap again. Same thing with Lion.

Shootist -

Let me tell you what I did. I installed ML on a 32GB thumb drive and copied the Mountain Lion installer to the Applications folder. Did the same with Lion. Also have just the installation USB flash drives for Lion and Mountain Lion on 8GB thumb drives.

Both work well and I'm happy to have both real systems on the 32GB flash drives and the installers on 8 GB flash drives.

I just can't have enough 'emergency' drives!

Clinton

I replaced my Cisco router with a Netgear router and my connection problem went away. I haven't a clue why so this may not help you but wanted to share.

I dont think there is a reliable fix from what I have read on this thread. For people using some sort of VPN server, your fix is fine. But the alot of us are just trying to get the Wi-fi to connect normally- without any sort of VPN service. I am going to try some of the suggested fixes tonight and will post my results.

I have a MBA and since I upgraded to ML Wlan/Wifi is not working anymore.

I cannot connect to a Cisco router nor the Time Capsule.

and no active VPN connection.

I need to use the cisco client to connect to my company, so it´s disabled at the moment.

The strange thing is that sometimes I got a connection but with a 164.x.x.x IP address, but with this IP address it´s not working. My home-network uses 192.x.x.x IP range

I have already deleted the old network configuration files without success 😟

Verizon Fios Actiontec router users only!

This is something that has been working for me since early Saturday.

I've passed it onto Apple. I know most of us has tried deleting our network setups with no luck.

Well this is what i did:

1: Deleted all networks and setting on my Mac again.

2: This time after that I did a Hard Reset of my router.

3: Rebooted my Mac

4: I then let our 2 Macs and Router set them selves up Automatically.

5: I left all settings to the default settings including Network name

6: Later I set my energy settings to deep sleep every 5 minutes.

This morning I decided to update my Onkyo receiver. I disconnected my router and moved it over to the receiver it needed to be hard wire connected to the receiver. The net worked fine there and when I put it back in the other room and connected to my PC every thing was still working wirelessly on our Macs.

I intentionally waited 2 days before I posted this and 36hrs before I passed it onto Apple.

I really don't know if this is just a fluke or if it works on other routers.

If you try it let me know your results. I'll pass it onto Apple.

I wanted to add my name to this thread. I started my own thread, but in another part of the forum. WiFi completely unreliable on 5Ghz (might affect 802.11n in general, but definitely 5Ghz.)

https://discussions.apple.com/thread/4175988?answerId=19181434022#19181434022

This worked for me- everything even time capsule is working properly now. It seems the ML install clears whatever DNS servers were listed- at least in some cases.

PHImhoff NH

Re: Wi-Fi Keeps Disconnecting in 10.8

Jul 27, 2012 6:34 AM (in response to meandmyevilclone)

I had the same problem

It seemed like it would hang on receiving new sites. Streaming music and video games worked OK.

In any case, after trying a bunch of different suggestions, the one that seemed to do the trick was changing the DNS settings to Open DNS. I think Mountain Lion reset the DNS to the modem DNS settings.

Now that the DNS is reset, it seems to be working great.

Under the advanced>DNS tab

Open DNS:

208.67.222.222

208.67.220.220

Same here, DNS update worked for me as well....

I have an early 2008 20inch iMac that drops from WiFi randomly after updating to ML. I also have a mid 2009 15inch MBP updated to ML that has no trouble at all. Both using AT&T/2Wire WAP.

I've tried every fix posted here but nothing works. I've updated DNS, rebuilt the system config, created a new location, used a static IP, used numerous different DHCP assigned IPs, rebooted, prayed, cursed, and even ****** on a spark plug. Nothing works for the iMac while the MBP chugs along without issue.

I'm fairly certain it's some mix of wirreless chipsets vs. WAP chipsets that is the problem. The question is: how long will it take Apple to narrow it down and figure it out and post a fix?

I really don't think it's DNS related. There are numerous posts suggeting switching to OpenDNS and other DNS servers but I can't see how that would help. At least not in my case.

I can watch in terminal as "ping www.apple.com" connects for a couple tries and then fails... then connects, then fails. I can also watch as my network is connected with an IP address for a few minutes, then disconnects, then connects, then disconnects all while sitting idle (or while pinging Apple).

This must be a dirver/chipset issue related to ML and 802.11x support.

Don't know if this will help anyone, but All Things Apple just posted a few more things to try, for both Lion and Mountain Lion. The main ones:

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

Fix #2: Change MTU Size to prevent Dropped Connections

I'd add one more important step from their additional suggestions:

Try changing the channel of the router you are connected to - especially if there are other wifi networks withing range of you that might be causing interference. And in another thread on this topic, folks have had some success by updating the router's firmware.

For those last two, consult your router's manual. For the first two, instructions are here:

http://allthingsapple.me/got-os-x-mountain-lion-wifi-problems-heres-the-solution /

Ok here's 1 fix that is working for me - for the last hour, so not able to say that it's a fix for everyone but give it a shot if you can.

My linksys router - e4200 has two networks and a guest network. Tried the Fix#1 - new network location and DHCP renew and Fix#2 - MTU size manual down from 1500 to 1453.

Since my default setting in my linksys config has a MTU size of 1500 - I didn't try changing that to match my MBA's MTU size to see if that worked. Might be a worthwhile experiment.

What worked tho - is removing my 802.11n 2.4 Ghz network (tried a different channel, but that didn't work either) and connecting instead to a 5Ghz network. Both networks are non-SSID broadcast, MAC-address checking and WPA2 personal. This has been working for the last 60+ mins. I get a 192.168. address and no longer get the self-assigned IP address. So if my fix is accurate, then whatever the issue was seems to related to firmware/802.11n/2.4Ghz spectrum networks. The 5Ghz so far works ok. But am continuing to see if it sticks.

what router make and model are you using ?