Q: Wi-Fi Keeps Disconnecting in 10.8

Ok, so I just got in the same boat as you guys who noticed wifi connection problems after the Mountain Lion upgrade.  I use a cable (comcast) router system.  It was squirly after the last upgrade, but Apple patced that up and it was fine after that.  Its wierd because I just installed 10.8.1 yesterday (took half a day to download) and the next thing you know evey time I woke it up I was off line.  It somehow affected the both the wifi signal and the data stream.  Sometimes I'd get a wifi signal, but no data and then sometimes no wifi signal.  It seems like there's a problem within 10.8 like there was with 10.7.  I just have to keep resetting my router.  At the moment that's the only way I can deal with it.

Ok, so finally after trying every possible fix I found here and on other forums, I found a temporary fix that worked for me.

10.8.1 did not fix the bug at all, but what seem to cause the problem is the WPA/WPA2. I did not try to use WEP.

I switched the WPA/WPA2 off (OBVIOUSLY A VERY VERY BAD THING) and suddnely wifi stays connected and works like a charm. At least I turned on MAC filtering, but I'm very dissapointed with this solution, since mac filtering is not safe at all. I hope, apple will fix the problem very soon as I don't want to have unsecured wireless connection!

I am really getting tired of turning my wifi on and off to get a signal.  I'm pretty sure the has to do with my 20 dollar upgrade of my OSX.  We (early 2011 iMac users) need a break.  We have work to do, people to talk to, and much more important things to do than spending 20 minutes after each sleep cycle turning on and off the wireless and resetting our routers.  HELP.

You can option-click the WiFi icon in the Menubar to see info about how you are connected.

Ha!  That's great.  I had no idea. 

so many useless functions in this bloatware

like websites with endless links all going to the same address

rather annoying ...

So, today I did a little testing, and I can deifinitelly say, that problem is with the AES encryption. My wifi works perfectly with wireless security turned off, with MAC filtering enabled. For obvious reasons I'm not happy with these settings...

So I tried to test the WiFi with the TKIP encryption instead of AES, and everything worked fine. The only problem is that TKIP is only supported in 802.11g mode, hence the speeds higher than 54mbit/s are not possible. But at least it's working, and it is more secure than WEP (or MAC filtering).

As soon as I switched back to AES and WPA/WPA2, the wifi dropped after 2 minutes...

An update from me on this. Apple called a while ago to get more info off of me, but I was on holiday. They've not called back so I assume that they have got the info from other people.

I still have the issues, for a recap:

If left alone for a while, my MBA will drop the wifi connection. Sometimes it grabs a new one and sometimes wont grab a new one until I touch the mouse/keyboard.

Due to this I often get iCal complain about an inability to contact the server. Given my iCal is talking to 3 servers for 3 different accounts I get 3 pop-ups which is very annoying.

It's a particular pain for me because I have 2 wifi networks depending whether I'm working in the office in the garden or in the house. I can see both networks in both places, but the signal is so weak (the house one when in the garage and visa versa) I get no bandwidth. The problem is I can force the Mac to go onto the garage wifi, but if the connection is dropped, it often picks up the weaker house wifi because it's is higher on the priority list. There's no point in swapping priorities because I'd just have the problem in the house then.

Despite renaming the location, changing MTU, DNS changes, etc... I was still dropping wi-fi on my iMac. I have a dual-band router so I connected to the 5GHz frequency and I have not had a dropped connection since. It has been almost a week and still good.

I don't have any drops on other devices on the 2.4GHz frequency with my iPad 2, wife's Nook Color, etc... but my iMac definitely had issues.

Ok I'm waiting.  You all know what I'm talking about.  Instantly, as you wake your iMac up, dropped WiFi.  I know this isn't an issue with my router because the un-Mountain Lion MacBook Pro jumps right on the system.  This started with the upgrade.  This same thing happened with Lion, but Apple found the patch and sent it as a sofware update to OSX Lion.  I'm still waiting and I'm sitting here hoping that I don't get dropped until I can send this to you guys out there.  Stand-by, waiting..... 

Ok this worked for me. I had the same exact problem. GO into system preferences, then click network.

After that click "Advanced"

Then there should be sort of a toolbar of options. CLick the last name named "Hardware"

Click the button that says "automatically" and switch it to manually.     (Configure)

Then click the button below it and change Standard to Custom (MTU)

Then the little number scale that says 1280-1500. Manually change the number to "1453"

and BOOM!   It works perfect

ps. your welcome

Since Apple introduced the new Airport Utility, 2.4Ghz and 5Ghz get they same SSID by default. After I changed my 5Ghz SSID and reconnected to it, I haven't had any problem.

Apple should change this in my opinion. By default both networks got different names using the previous Airport Utility.

Thank you!! Out of all the solutions, this has been the only one to work. I made the changes early this morning and not a single drop from either of my time capsules.  

I have a mid 2011 iMac and this problem has recently kicked in and is driving me nuts. I know it's not my router because all other devices are working fine. Every 15 - 30 minutes I have to turn the Wi-Fi off and on to use the internet.

No problem buddy same thing happened to me and it worked for me

Here is what worked for us. My wife and I each have a Macbook Air, one has this issue and the other is just fine. Same router, same everything. On the one with the issue we made the IP address static. If you can log into your wireless router you can sometimes add a reserved IP or simply edit your DHCP settings to only include a certain range, say 50 IP addresses. If you can add a reserved IP that may work for you. Just add the IP for the device that is having the issues. If you're in your network settings you should see it pop up the IP address when it tries to acquire it and then drop it. If you cannot reserve an IP go into advanced settings in your network settings, then TCP/IP, and choose Using DHCP with manual addres from the drop down. Enter an IP address that is not in the DHCP range, 192.168.1.100 for example. If you need more help with this email me at owen at borseth dot us.