Q: BUG: Mountain Lion kills wifi speed when using airplay or time capsule

Yeah, good question ... no it doesn't integrate with airport, you have to disable that. In fact the instructions that came with the dongle weren't very good but after a support call they directed me to RALinks website for some drivers. Once those were installed they come with a connection utility which seems to be functional, if not the prettiest thing. Link speed is quoted as 150Mb/s.

Thank you to everyone on this thread for all the information. I was experiencing extremely slow Time Machine backups after upgrading to Mountain Lion. Otherwise the WiFi speed seemed to be normal. I am using a MacBookPro 3,1 with a recent Time Machien. The Time Machine Wifi network is extended with a 2012 Airport Express.

Downgrading the IO80211Family.kext from 5.0 to 4.2 using Kext Wizard solved the problems for me.

Cheers

Martin

YAY! Downgrading the kernel etension on my MacBook Pro 3,1 worked for me too. My first backup after upgrading to 10.8 was about 50 GB and it took 36 hours to finish 600 bytes. Not megabytes or kilobytes, but BYTES. I tried all the Time Machine and Time Capsule troubleshooters, tests, diagnostics, workarounds, and resets I could find, but nothing! A wired connection worked fine. Booting into Windows even worked, but 10.8 just wasn't having it. I wasn't willing to be tethered to my Time Capsule to do Time Machine backups every hour. I finished the downgrade of the kext and everything is back to normal!

Yes. Restoring the IO80211Family.kext version 3.2 from Mac OS X 10.6.8 solved this problem for me as well. The AirPort connection stays now at full speed (MCS-Index 13 - 15) during Time Machine backups.

With the IO80211Family.kext version 4.0 from Mac OS X 10.8.2 the speed of the AirPort connection was dropping to MCS-index 0 as soon as Time Machine started to mount the remote Time Machine volume. I always needed to switch between two identical AirPort settings in order to reset the wireless connection while Time Machine was doing the backup.

FYI, after backing up the v4.0 kext, I restored the v3.2 kext directly from a Time Machine backup of the old system and rebooted. I am aware that this is not recommended, but  it worked for me.

Thank you very much aysm?, this tip has solved my problem.  And thanks also to Gunny Sack for the pointers and everyone else who has contributed to the solution.

I'm a late adopter, I've just moved up to ML.  And after a few seconds the streaming audio from itunes to airport expresses died.  And again.  And again.  I've got a 2007 MacBook Pro 3,2.

I first tried the SL kext which worked but in maybe a half hour there were two short dropouts of the itunes to the airport expresses stream.  So I scavenged the Lion version, 4.2, from the backup I made before moving to ML and that seems to be working fine now.

I'd also noted that wifi took a very long time to "come back" after sleep in ML.  Hopefully this patch will solve that too.

So once again thank you very much.

Any word if the OS X.8.3 Update fixed anything?

The IO80211Family.kext has been updated to version 5.2.2 in the OS X 10.8.3 update. I've been testing it for about 5 minutes and so far I've had no streaming drop-outs. So, it seems as if the bug has been fixed but I'll have to test it for longer just to be sure.

Well, bad news. The bug isn't fixed. I was streaming music to my ATV 2 for about 10 minutes when it abruptly stopped and the transmit rate drop to 13.

*Sighs*

do u have to replace the .kext after each update? or did you remove the one from X.6 to try the updated one or did the update replace the 4.0 to the 5.2.2?

besides the streaming and time capsule back up issues how does the 2007 MBP react to X.8.3? improvement over X.7.5 or should i just stick with X.7.5 and forget about X.8?

It depends if Apple includes an updated IO80211Family.kext in an incremental update. I downloaded the 10.8.3 update and opened it with Pacifist first to see if there was a new kext, which there was. If you install a combo update, then you'll always will have to re-apply the kext workaround mentioned in this thread.

10.8 is an improvement over 10.7 in several ways so it was worth it for me. But if you're happy with 10.7, I don't see any urgent need to upgrade. 10.9 is supposed to be released this summer, but I don't know if our old laptops will be capable of running it, so 10.8 might be the end of the line for those of us still using the MacBook Pro 3,1.

Well, I applied the 10.8.3 and it is behaving like it did before. Which resounds with unfortunate verbalities.

I reapplied the Snow Leopard ktext to no avail.  Seems Apple has broken our work around.

No, 10.8.3 won't fix it.

Apple, please do something!

(i.e. https://discussions.apple.com/message/21319397#21319397)

MacMunfordGB,

Check the version number of the kext in your Extensions folder to ensure that it was installed properly. I reapplied the kext (although I used the kext from 10.7.3) and it's working fine.

It shows version 3.2. Is that correct? It seems to be behaving after the reboot. I do seem to run into it more when I'm streaming to Apple TV, but that means additional testing.

Thanks Gunny,  GB

Yeah, version 3.2 is the Snow Leopard kext. Version 4.1.2 is the version I'm using from 10.7.3. If you want version 4.1.2, let me know, and I'll send you a link.