Wifi Constantly Dropping in Lion

I finally was able to get things stable for more than 48 hours on a 5 GHz 802.11n network. I am using a Linksys Cisco E4200 with my iMac 27" (mid-2011). Since the iMac only supports a limited number of 5GHz channels I manually set the Linksys to work on channel 153 - 5.765 GHz with WPA2 security.

You can see what channels your particular Mac supports: Apple Menu > About This Mac > More info... >System Report > Network > Wi-Fi > Suported Channels

levimaaia wrote:

I finally was able to get things stable for more than 48 hours on a 5 GHz 802.11n network. I am using a Linksys Cisco E4200 with my iMac 27" (mid-2011). Since the iMac only supports a limited number of 5GHz channels I manually set the Linksys to work on channel 153 - 5.765 GHz with WPA2 security.

You can see what channels your particular Mac supports: Apple Menu > About This Mac > More info... >System Report > Network > Wi-Fi > Suported Channels

Using a fixed channel as a solution may be the answer for people with huge amounts of other users around them. The automatic setting, may, in fact create more problems in this environment, if the radio keeps shift frequencies, causing your computer to have to constantly skip around. Even on 5ghz, there may be enough noise that a fixed frequency is the right choice. Look to see what's going on around you and pick a lightly loaded frequency.

There is a cool Dashboard widget called Airlock that can help you survey Wi-Fi networks. It shows you the names, types and channels of all of the networks in range. Pick a 5 GHz channel (they are all three-digits) not already listed that is supported by your Airport card (not all 5GHz channels are supported).

http://www.pimley.net/projects/#airlock

I think one of the problems with the automatic channel selection with non-apple 802.11n 5GHz routers is that they sometimes skip to a channel not supported by Apple Airport cards leaving Apple devices out of the loop and offline. A manual channel selection may be appropriate in this case even if you are not surrounded by other networks for the simple fact that the chance remains that the router could choose an unsupported channel as long as it is set to auto.

I tried channel 11; it worked for a little bit, but it eventually started dropping.

I switched to channel 1, now I am on day two. Wifi has no issues when after waking, and no random drops.

Wireless experts recommend channels 1,6, and 11, so I would start with those settings.

I hope you guys have as much luck as I did with this solution.

The deal is how the channels are used by other users and the choice of 802.11b/g/n they are using. Look at what's going on around you, and pick something open or with fewer users. Using Channel 1, 6 or 11 is the right choice because it keeps users separated from each other, but if someone else is not on one of those channels, it may interfere with two of these channels, and you'd need to smartly pick another channel to be away from them.

If you look back in this thread you'll see that I have been having connectivity issues since my upgrade to Lion. I have tried every proposed solution here, I have spent hours on the phone with my ISP, I have spent hours on the phone with Cisco, I have spent, cumulatively, days either on the phone or at Apple, every one of my friends, acquaintances, colleagues, Starbucks baristas, lunch counter lady, strangers on the street, anyone who will listen know my connectivity problems as well as I do, I have exhausted my patience and reached the absolute limits of my technical abilities. The result: It still happens, some days more frequently, some days hardly noticeable, Apple couldn't be kinder or more helpful (except, of course, for fixing the problem) or understanding, and I have begun muttering and grumbling to my iMac much the way I muttered and grumbled to my HP PC before I chucked it and switched my whole life over to Apple a couple of months before Lion came out. That's all understandable, but the scary part is that I caught myself thinking earlier today, "Don't worry, it'll all be better when they release and you install Mountain Lion . . . That'll fix everything!" You would think I'd have learned by now.

Sincerely, a heartfelt good luck to all who are experiencing these issues along with a hope that These issues will be resolved soon.

My two cents. I've seen this suggestion on this discussion before, but never tried it until recently. From the posts, it obviously hasn't worked for everyone...if it had, this discussion wouldn't be an incredible 122 pages! Having said that, this worked for both me & a friend who was experiencing the exact same problem (both running Lion 10.7.4 on iMacs with current Airport basestations) And that is: simply deleting the SystemConfiguration folder from the root Library and then rebooting. Important: the Root Library, not the User Library. HD>Library>Preferences>SystemConfiguration.

After rebooting, the folder rebuilds itself.

I'm always leery of messing around in the root level system, so if you are too, don't completely trash the folder you deleted...you can always retrieve it frrom the Trash if you don't empty the Trash. I kept a copy on the Desktop just to be safe but I haven't needed it.

I know this may seem too simplistic given all the other solutions, workarounds, etc.....All I can say is, I don't understand it, but it worked for me.

Good luck.

Further update:

My iMac stays connected when I use "G" mode to a "G" only AP. I've recently acquired a new WAP (e4200 Dual Band) and using the 5GHz band, I too stay connected. I still cannot stay connected to my older airport extreme (single band N).

Until I just happened upon this new Cisco WAP, I had been plugged-in (ethernet) directly.

Maybe now, I can remove the tripping hazard from my office.

FWIW I am using an old Airport Extreme and switch to Channel 8 from Auto and it has worked very well for the last 48 hrs or so. Best solution yet for me.

::crosses fingers::

kriskjellquist wrote:

FWIW I am using an old Airport Extreme and switch to Channel 8 from Auto and it has worked very well for the last 48 hrs or so. Best solution yet for me.

::crosses fingers::

It would be best if any users of fixed channels on 2.4ghz used channels 1, 6 or 11. Any other channel usage will cause interference on two "segments" simulaneously for 802.11n users.

Same problem here. Wifi was perfect with snow leopard and now drops constantly with lion. So with everyone having the same problem this is obviously an iOS problem. Does anyone have a solution?? This is no small issue! This needs to be fixed today.

Mikejfix wrote:

Same problem here. Wifi was perfect with snow leopard and now drops constantly with lion. So with everyone having the same problem this is obviously an iOS problem. Does anyone have a solution?? This is no small issue! This needs to be fixed today.

This conclusion simply isn't valid; coincidence does not indicate causality.

I've stated several times in several posts how this can happen and not be iOS/Mac OS X's fault.

Have you tried the obvious number one debugging step and made sure your router's firmware is the most up-to-date available from its manufacturer?

I've posted it at least twice before but IF you have a late 2009 iMac (you can see this from About This Mac->More Info...) then the problem is in the upgraded Lion driver for your Atheros wi-fi card. It seems Apple updated this driver to add the Air Drop capability but the side effect is that it causes the wi-fi dropping, Simply revert to the Snow Leopard version of the driver (easy, see link below) and all is well except your AirDrop will go away - a small price to pay IMO for a working wi-fi. I have certified this multiple times. Go here for the only solution that really works:http://rys.sommefeldt.com/2011/09/04/osx-lion-wifi.html.

There may be more than one problem reported on this discussion for sure, and some may be not Apple's fault, but this one 100% for sure is. But if you have a Late 2009 iMac with the Atheros wi-fi chip set and everything went south once Lion was installed, this should work for you.

Sorry I don't buy it... this is an OS issue. When I reboot into Snow Leopard it simply works. NO PROBLEM!

Same computer, same wi-fi, same everything except Snow Leopard instead of Lion! I cannot accept it is not Lion.

Here is hoping Mountain Lion is a winner.

I solved my problem by hard wiring up the house with CAT-5. Got tired of waiting. Connection speeds are simply amazing.

Mike

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