Airport problem

I just read your "fix-it". My problem was after the keychain upgrade the airport card could not be seen! I deleted the AppleAirport2.kext file from the library...still does not show an airport card installed. Any other udeas.

I have been struggling with this issue aswell. It seems to only occur in PowerBook G4 machines. I have tested this with a MacBook Pro and it does not happen.

IMPORTANT: To find your Wireless Transmit Rate, ALT-CLICK the airport menubar icon.

Symptoms:
When you connect to your wireless network, your transmit rate will be 54. (if you're using the 54g standard). If you start up a download or something that occupies your bandwidth (even LAN traffic), you will notice that the transmit rate drops to 11, then to 3, then to 1 until finally your downloads will drop, your ichat connections will fail and your browser will not load pages.

*My attempts at solving this:*
- Changed the wireless channel between 1 and 11. DOES NOT FIX THE ISSUE.
- Changed encryption to shared key/open key. DOES NOT FIX THE ISSUE.
- Removed encryption. DOES NOT FIX THE ISSUE.
- Changed DTIM, RTS, Fragment length settings. DOES NOT FIX THE ISSUE.
- Forced 11b mode. DOES NOT FIX THE ISSUE.
- Forced transmit rate to 54Mbit/s. DOES NOT FIX THE ISSUE.
- Downgraded the firmware to an earlier version. DOES NOT FIX THE ISSUE.
- My access point is a Conceptronic C54APT. There is a hack that allows you to flash it to a D-Link DWL-2100AP. I flashed it and it DOES NOT FIX THE ISSUE.

Solution:
- I have another access point in the house (although, it does not reach my entire house, which is why I have the Conceptronic). It is a linksys WRT54G. I can CONFIRM that this issue does NOT occur with the linksys. It works great.
- Just 30 minutes ago, I remembered that my access point has a hidden feature to boost the transmit power. I boosted it to 24 dBm and for the last 30 minutes, I downloaded over 1GB of data and was not disconnected however the connection is extremely unstable. The download speeds vary between 300KB/s and 1MB/s whereas it used to give me a stable 1MB/s in Tiger.
- Before you tell me that the problem is my Conceptronic access point, remember that it always worked PERFECTLY in Tiger. (aswell as any other OS or device such as a PDA, a Nintendo DS and a Nintendo Wii)

*My opinion of what's happening:*
I believe this is because of the new self-tuning TCP feature. If you alt-click the airport button a few times during a download, you will see that Leopard adjusts your transmit speed so that a more stable connection is possible. This adjustment is what is causing the problem.
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Now my question is: *how do I disable the new self-tuning TCP feature?*

Also having a problem with my D-Link access point. I would like to add I seem to be having the same type of symptoms with my Verizon Wireless ExpressCard connecting to their 3G network. A couple of odd things in system.log:

Note: Frequent transitions for interface en1
network traffic reduction measures in effect

I to am having airport issues which were not there before leopard.

On the G4 Powerbook, airport connection drops in and out all the time.
The same on my G5 iMac.

Im using a linksys WRT54G as my router in WDS mode with 2 x Airport Express bases also in WDS mode, which has worked flawlessly with Tiger for over a year.

Gonna hold off putting Leopard on my MacPro until this issue is fixed.

On a slightly related note i get the same problem of lost network connection and stalls when i connect the g4 and g5 together with IP over Firewire.

also both G4 and G5 had a Erase & Install, not an upgrade. so the systems are clean.

I have a PPC machine though. Apple really needs to address this.

I have VMWare 1.1 installed and my wireless connection is still slow when connected via N to a first gen Airport Base Station. I have an RSSI of -54 which is good, rate is 270 but speakeasy.net speed test says I only have a 499kb/sec download rate. I can get 2500KB/sec down on the hardwired connection.

When I connect to my G Air Port Base Station then I get good rates.

I'm having a very serious problem with my wireless connection as well. After installing Leopard, every time I try to download a file that's large (>30MB) I lose the signal. Turning AirPort off and turning it back on will re-establish the connection and resume download, but it will die after about 15 seconds. I have to repeat this process over and over again to finish the download. Has anyone experienced this problem? This problem cannot be reproduced when I boot into Tiger so this must be Leopard specific issue.

Wireless router: Linksys WRT54GL (latest firmware)
AirPort Extreme Card installed on the Power Mac G5.

Hi tryu, I have EXACTLY the same problem as you.

I posted above some of the things I tried, but I neglected to give an example like yours.

Yesterday I was downloading Firefox (a 17MB file) and it disconnected 3 times. Every time it did, I had to turn off the airport and turn it on again, because it would NOT find my wireless network.
My Tiger is fine aswell. You are not alone.

*Apple needs to fix this ASAP. It makes Leopard useless for me.*

Exactly the same issues here.
Using a fresh install of Leopard on a G4 15" PowerBook with Airport Extreme to a Linksys WRT54G router.
Connection starts out really good but soon comes to a screeching halt.
Using a wired connection to the same router works perfectly, so the issue is confined to wireless.

Like most people I'm thinking the self-tuning TCP is causing issues as no problems have existed previously.

I too am having problems with AirPort disconnecting every half hour or so. I posted this elsewhere:

Suddenly after upgrading to Leopard, both Safari and Mail report that Mac OS X isn't staying connected to the Internet. I'm using AirPort and a cable modem and it's always been reliable before. But now there seems to be something jumpy/fishy going on in the AirPort menu in Leopard's menu bar. The list of available networks changes very often and although my own network remains checked, Network Diagnostics shows that I am indeed getting disconnected often and for long lengths of time. But everytime I restart my Mac, my Internet connection is restored.

I had fully expected BETTER networking in Leopard, not WORSE.