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Satoru Murata

Q: Slow Wireless LAN in Leopard

All right, I've spent the past 12 hours (on and off, of course) looking through all the threads in here, doing a lot of experimentation, and a bunch of clean installs and whatnots, and I've decided to start a new thread, since in many of the said threads, some people seemed to have similar issues, but the other issues in the same threads seem to be different problems, and it just becomes confusing when you try to trouble shoot something and people are talking about different problems.


So, this thread is specifically for people who satisfy these criteria under Leopard:

1) You're having issues with very slow file transfers in your *local network* when at least one end is connected wirelessly; that is to say, when both ends are connected to the router via ethernet, you see no problem at all.

2) Your wireless connection doesn't display problems when connecting to the internet.

3) It is not specifically an 802.11n issue; i.e., the problem can be duplicated when in Mixed b/g only mode and/or using an 802.11g router.

4) It's not a router connection issue; i.e., your wireless connection isn't being dropped, and you are able to find your AP and connect to it without any problems.




So basically, that more or less sums up my problem. My equipments:

MacBook Core2Duo 2.2GHz, 802.11b/g/n, OSX 10.5.2
iMac Core2Duo 2.13GHz, 802.11b/g/n, OSX 10.5.2
Router 1: TRENDnet TEW-631BRP (Draft N router), H/W V3.0R, FW v.1.0.3.7
Router 2: NETGEAR WGR614 v.5 (g), FW v.1.0.3_1.0.3

Internet: RCN Cable, 20Mbps/2Mbps


In my usual setup, the iMac is connected via Ethernet and the Macbook is connected wirelessly.


I know that this is a Leopard problem, but I'm not so sure it's a 10.5.2 specific problem. Let me explain.

I'd been using the TRENDnet more or less happily for the last couple of months. My iMac and Macbook have been in sync in terms of Leopard versions, so I know things were OK till last night when I first noticed problems. Transferring a large video file from the iMac to the Macbook would start off fine, then really slow down, and finally almost completely halt. Naturally, I blamed 10.5.2.


After trying all the different "fixes" in the Leopard/network related threads with no avail, I tried booting my laptop into Tiger (10.4.11) installed on an external HDD. Voila, wireless file transfer speed is fast at around 8MB/sec (obviously using N). I did a fresh install of 10.5, and the speed immediately dropped down to 1-2MB/sec, although not necessarily stalling. Then, updating to 10.5.2 slowed it down more, and now the transfers will sooner or later almost completely stall.


Again, I tried all the suggested remedies (use b/g Only mode, adjust RTS/Fragmentation thresholds, use WEP instead of WPA, delete all the Network Services in System Preferences -> Network, etc., etc.). Nothing helps. I tried swapping the router to an older Netgear (802.11g/b), and it's the same deal, so it's not a router issue.


A definite characteristic is that the transfer seems to stall after a certain period of sustained transferring; i.e., this will usually only happen when transferring large files (>200MB). If I were to download a folder with 600 JPEG files @ 1MB each, there won't be a problem, and the transfer rate will be pretty fast (although not as fast as under Tiger @ 7-8MB/sec), and it won't stall. It's only when I try to transfer big video files, etc., that this problem occurs.



If you are having similar issues, please share your experiences, suggest remedies, offer insights. I will try to answer any question you may have and that I may have missed to address.


PLEASE: if your symptoms are different from what's listed up there, please try to refrain from posting here, unless you are absolutely certain that the issues are related. Thanks.

iMac 20" Core2Duo 2.13Ghz/ MacBook 2.2 GHz Superdrive (White), Mac OS X (10.5.2)

Posted on Feb 14, 2008 12:39 AM

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Q: Slow Wireless LAN in Leopard

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  • by jonathanbordeaux,

    jonathanbordeaux jonathanbordeaux Mar 9, 2008 11:37 AM in response to JOHN ALBERGO
    Level 1 (0 points)
    Mar 9, 2008 11:37 AM in response to JOHN ALBERGO
    YAAY! This delayedack hack fixed things for me! I'll just have to remember to uninstall it now before any sort of upgrade in 10,5,3 or to QT or whatever Airport update they might bundle a fix into.
    Crazy that a hack used back in 2006 becomes useful again!!
  • by Tom Robinson5,

    Tom Robinson5 Tom Robinson5 Mar 9, 2008 1:01 PM in response to jonathanbordeaux
    Level 2 (180 points)
    Mar 9, 2008 1:01 PM in response to jonathanbordeaux
    I don't think it qualifies as a hack, it's adjusting a low-level preference--in fact if you reboot you'll need to set it again.

    It's certainly fixed things for me (thanks guys!) I have a MacBook Pro and iMac on an Airport Express network. After upgrading to 10.5.2 iTunes would start to stutter after getting 2 mins into a song, and ChronoSync's transfer rates would plummet on larger files. Finder copies were fine.
  • by kenneyc,

    kenneyc kenneyc Mar 9, 2008 8:04 PM in response to Satoru Murata
    Level 1 (0 points)
    Mar 9, 2008 8:04 PM in response to Satoru Murata
    Almost identical issue, if not identical. I tried transferring the downloaded iphone sdk from my powermac to my macbook, would start out a nice transfer speeds that would drop to around 30KB/sec quickly. One thing I tried, that seems to have helped, is I tried using transmit to copy the file via sftp over my network, and got 1600KB/sec until the file was done. Not 802.11g speeds, but a lot better. Screen sharing works great, an SMB transfer using the finder suffers the same speeds as a normal AFP file transfer. AppleTalk is off on both machines.

    Details:
    PowerMac G5 Dual 2.0 running 10.5.2, hard wired to a gigabit ethernet switch
    MacBook Core2Duo 2.2Ghz running 10.5.2, connected via airport
    AirPort Extreme 802.11g (the UFO looking one), with a gigabit ethernet switch connected to the LAN port.
  • by Satoru Murata,

    Satoru Murata Satoru Murata Mar 9, 2008 9:46 PM in response to kenneyc
    Level 1 (15 points)
    Mar 9, 2008 9:46 PM in response to kenneyc
    Yup, sounds right. My experiments also show that AFP and SMB are affected alike, but FTP is A-OK. So definitely, this is a combination of problems (wireless, transfer protocol, uploading vs. downloading, etc.).
  • by Latcarf,

    Latcarf Latcarf Mar 10, 2008 12:29 PM in response to Satoru Murata
    Level 1 (5 points)
    Mar 10, 2008 12:29 PM in response to Satoru Murata
    I've got no solution but I have the same problem. I have a Mac Mini (PPC) wired serving files, any wireless laptop has the speed problem exactly as you described at the beginning of the thread. Problems did not start until I upgraded the Mini to 10.5 from 10.4
  • by barthrh,

    barthrh barthrh Mar 10, 2008 6:49 PM in response to Satoru Murata
    Level 1 (25 points)
    Mar 10, 2008 6:49 PM in response to Satoru Murata
    I have the same problem and found a possible "solution". It's more of an observation, really.

    Let's say that I'm having slowness. If I log into another account on the MBP and the connect to that share I can copy to my heart's content with no speed penalty. Not only that, it speeds up in the account that had the problem as long as I remain connected in the second account. As soon as I disconnect that second account, it jams up again in the original. I am connecting to the AFP share as the same user, but from different accounts.

    Has anyone else noticed this?
  • by mattsigal,

    mattsigal mattsigal Mar 11, 2008 1:59 PM in response to Satoru Murata
    Level 1 (0 points)
    Mar 11, 2008 1:59 PM in response to Satoru Murata
    Just to update... The delayedack fix is a bandaid over the real problem. Since applying the fix, wireless transfers have been at more acceptable speeds (although not what they used to be before 10.5.2), which I'm fine with.

    What I'm not fine with is the fact that MediaLink (a basic media streamer for OS X to PS3) is still completely broken by this. Even more infuriating, the PS3 and the iMac are both connected VIA ETHERNET to my router. There is no reason at all for this! I can't even stream movies - all I get is a black screen that, after waiting a few minutes, culminates in a network error (plus a slew of DNLA errors while browsing, but those happened before too).

    If anyone knows of another band-aid that might make MediaLink somewhat usable... Please let me know!
  • by thebruce,

    thebruce thebruce Mar 11, 2008 3:13 PM in response to Satoru Murata
    Level 1 (0 points)
    Mar 11, 2008 3:13 PM in response to Satoru Murata
    I have the exact same problem.

    Re-installed tiger -> perfect transfer speeds over wireless.

    Fresh leopard install ->slow AFP and SMB. Internet is as fast as ever.

    Have tried multiple routers, wireless channels etc.
  • by Latcarf,

    Latcarf Latcarf Mar 11, 2008 5:53 PM in response to Satoru Murata
    Level 1 (5 points)
    Mar 11, 2008 5:53 PM in response to Satoru Murata
    Until this is fixed, here's my workaround:

    I am tunneling AFP through SSH (port forwarding). Since SSH isn't affected, AFP running over SSH isn't affected and I can transfer files just fine.

    On the "Remote" machine (i.e. wired file server or whatever):
    Open System Preferences and click the "Sharing" icon.
    Check the box next to "Remote Login"

    On the "Local" machine (i.e. wireless laptop, etc):
    Open "Terminal" app (/Applications/Utilities/Terminal.app)
    Use SSH to connect to the remote machine and "port forward" to AFP on the remote machine. Enter the following line and hit return:

    ssh -L 10548:127.0.0.1:548 username@remotemachine.local

    (here the first number is a local unprivileged port number - 10548, the second number is the "localhost" address - 127.0.0.1, the third number is the AFP port on the remote machine - 548). In place of "username" enter your user account name for the "remote" machine. In place of "remotemachine.local" user either the ip address or .local name of the "remote" machine.

    Enter the user account's password for the remote machine when prompted and hit return.

    Once you've logged in you can connect via AFP:
    In the Finder either hit command-k or choose "Connect to server..." from the "Go" menu.
    In the "Connect to Server" dialog, enter the following for the server address:

    afp://127.0.0.1:10548

    In a moment the AFP password dialog will pop-up and after you enter your user name and password for the remote machine, you'll get the "Choose volume to mount" dialog.

    While you still have the SSH connection up, you'll maintain the AFP connection. If you want to use this workaround for multiple "remote" machines, you'll need to use a different unprivileged local port for each one (10548, 10549, 10550, etc...).

    When you're done transferring files, unmount the AFP volume and simply type "exit" in the Terminal window to close the SSH connection.

    It takes a little work but I guess that's why they call them "workarounds."
  • by herfurthba,

    herfurthba herfurthba Mar 12, 2008 7:38 AM in response to Latcarf
    Level 1 (0 points)
    Mar 12, 2008 7:38 AM in response to Latcarf
    I had the same issue when copying files between my G4 and my MacBook Pro - both running 10.5.2.
    After some longer calls with Apple's support today I restarted the MacBook Pro in safe boot mode (hold shift key during restart). A few more caches get cleared during the reboot and afterwards the transfer rate is up to 4MB/s according to iStat Pro - and that is 32mbps constantly during a file transfer of 16GB. I know my Airport Extreme should be capable of 54mbps, but it works fine for me now.
  • by Jowie,

    Jowie Jowie Mar 12, 2008 7:52 AM in response to herfurthba
    Level 2 (205 points)
    Mar 12, 2008 7:52 AM in response to herfurthba
    Interesting - are you saying that a simple reboot in safe mode followed by another restart will clear the problem?
  • by paldari,

    paldari paldari Mar 13, 2008 2:04 AM in response to Jowie
    Level 1 (0 points)
    Mar 13, 2008 2:04 AM in response to Jowie
    OK I've tried rebooting in safety mode and restarting again.

    This is what I have tested.

    after rebooting twice one safe boot and one reboot.

    I found sending to the other computer was fast (I'm not sure if this was fixed, or I've always checked pulling files from the other computer and this was the first time I've tested pushing files.

    so initiating pushing file from one computer to the other one was fast.
    but pulling file from the other computer was still slow.
    this was true both ways = the direction of file transfer didn't matter. just if I was sending file
    or pulling file made the speed difference.

    then I did the sudo sysctl -w net.inet.tcp.delayed_ack=0 trick and found it fixed
    the pulling file was fast again.

    rebooting seemed to help. the fastest file transfers so for. it was better then just
    doing the sudo sysctl -w net.inet.tcp.delayed_ack=0.


    Hope that helps and gives more clues to fixing the problem.


    Thanks
  • by mnementh23,

    mnementh23 mnementh23 Mar 13, 2008 4:20 AM in response to Satoru Murata
    Level 1 (0 points)
    Mar 13, 2008 4:20 AM in response to Satoru Murata
    Just adding my name to the list here. Two macs - an iMac and MacBook, both running Leopard. iMac's connected via Ethernet, Macbook is wireless. Internet's fine but transferring files is glacial.
  • by jonathanbordeaux,

    jonathanbordeaux jonathanbordeaux Mar 13, 2008 10:13 AM in response to Tom Robinson5
    Level 1 (0 points)
    Mar 13, 2008 10:13 AM in response to Tom Robinson5
    Tom Robinson5 wrote:
    I don't think it qualifies as a hack, it's adjusting a low-level preference--in fact if you reboot you'll need to set it again.



    No that's the point of the script that John Albergo posted: it resets the DELAYED_ACK setting each time you restart......
  • by naturalhighNZ,

    naturalhighNZ naturalhighNZ Mar 13, 2008 3:23 PM in response to mnementh23
    Level 1 (0 points)
    Mar 13, 2008 3:23 PM in response to mnementh23
    I have the exact same problem. My internet seems fine but I no longer can stream using Connect360 to my Xbox 360. Basically I just get a black screen where I used to be able to stream movies easily. Sometimes I will get a fragment of a movie but it will end up hanging while buffering. It worked fine for me for a while, but for me the problems began with 10.4.10 and 11. Now I have upgraded to Leopard and the problem is worse than before. I cannot even stream music half the time (sometimes it will work temporarily).
    I have an RA to return it to an Apple Tech I am just not sure if they will find something as its such a difficult problem to source. I have gone through 3 different routers with this and am now pretty confident the problem lies with the Mac as other PCs on the network have no problem whatsoever.

    Is there a test that I can get an Apple tech to do with my Macbook that will expose the problem? Thanks!
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