dblum
Level 1 (0 points)

Q: Looking for help to improve Airport performance over LAN (WAN is fine)

Ok, I've read through several threads on this forum that address problems people are having with slow performance with Airport. I've also checked out all of the Apple KBs that address Airport, recommended settings. Unfortunately my issue isn't addressed by anything I've read to date.

 

The bottom line is that both download and upload performance between any of my devices and the internet is fine, no problems. I am paying for 30MBps download from Verizon FIOS, I routinely get 20, and I'm guessing that the delta is Verizon's problem, not my network's. However, streaming from my media server to another device on the wireless LAN is a different story entirely. I get somewhere between 1 and 2 MBps, tops, and this poses big problems for streaming music and movies.

 

My network is comprised of 3 Airport Expresses. One of them is a MC414LL/A model. This one is connected to my Verizon FIOS Actiontec MI424WR router (which I have set to bridge-mode according to the instructions provided at http://www.dslreports.com/forum/r17679150-Howto-make-ActionTec-MI424WR-a-network -bridge) via CAT5 ethernet. This Airport Express is set to "create a network" network mode, "802.11 only (5GHz) - 802.11b/g/n" radio mode (although I have also tried "802.11 only (5GHz) - 802.11/n only (2.4 GHz)" radio mode, and this didn't solve the problem). Finally, I have chosen 2.4 and 5GHz channels that have little interference (2 and 161 respectively). My other two Airport Expresses are MB321LL/A models and are set to "Extend a wireless network" network mode, with the 5GHz network chosen as the network that they extend. (I have tried switching over to having them extend the 2.4GHz network, and performance gets worse, not better.)

 

I am using a late 2009 Mac Mini as a media server. It is connected to the 5GHz network (though I've tried the 2.4GHz network), and it runs XBMC and JRiver media servers (not simultaneously, either one or the other.) I have a PS3 and a Sony Blu Ray player, each plugged into one of the MB321LL/A Airport Expresses via CAT5 ethernet, and I stream media to each of these devices via one or the other media server (both devices are DNLA-enabled). My Mac Mini has a 3TB external hard drive connected via FireWire 800, which is where all of my media resides. In addition to streaming media over the network, I have a TV plugged directly into the Mac Mini. When I play media to this TV, performance is outstanding, so I'm confident my poor performance to the PS3 and Sony BDP is a network issue, not an issue with the external drive.

 

Although my building has several other wireless networks, only one of them is 5 GHz, and it isn't using channel 161. The 2.4 GHz band is crowded with several networks, although channel 2 is usually in the clear. I have tried switching let Airport choose a channel automatically, and I haven't noticed a difference. It has occurred to me that the problem could be with how I bridged the Verizon Actiontec router and not with any of the Airports, but I don't get any errors (e.g. double NAT errors, which some people who have bridged improperly get), and I am pleased with my download and upload speeds to the internet. The issue is only on my LAN. Finally, yes, all of my firmware is up to date, version 7.6.3 on all three Airport Expresses.

 

Can anyone offer me suggestions for how I can get better performance streaming media from my server to the two playback devices? Since all 3 Airport Expresses support 5GHz, I'd have thought I'd be able to take advantage of 802.11n speeds when streaming between them. (MB321LL/A  supports "Draft N", but does this matter?) With the settings that I'm currently using, I can't stream faster than 2MBps (and that's on a good day), which is below what I ought to be able to get rom 802.11g. This is especially problematic when I try to stream hi res (96 MHz / 24 bit or higher)  music files, whether uncompressed or compressed. I hear awful pulsing sounds through my speakers. If I pause the track and let my streaming device buffer, I might get 10 or 15 seconds of clean playback, but then it starts the pulsing again as soon as the buffered music is finished playing. On occasion when I stream music from my iPhone via Airplay to one of the Airport Expresses, I get clean playback most of the time, but on occasion the music cuts out. (It's my understanding the Airplay requires ~800 Kbps, which seems consistent with my LAN speed usually being between 1 and 2 Mbps but sometimes dropping).

 

I have iStubler and I've used the Apple network diagnostics -- these are the tools that led me to choose channels 2 and 161 for 2.4 and 5GHz respectively. I'm sure I could be using these tools to learn more about my network's performance, but I'm sure what to look for.

 

Thanks for your suggestions.

Posted on Aug 10, 2013 9:34 AM

by Tesserax,Solvedanswer
Tesserax Tesserax
Level 9 (54,906 points)
Wireless
A:

Most Internet speed test utilities measure the overall bandwidth between the target server and your network client. As you are aware the local network is just one component of that overall bandwidth score.

 

I would expect that any bandwidth performance issues on any of these components would affect the overall score. Where you will potentially see the best performance in improving the local wireless network bandwidth is for file transfers, streaming, etc. between devices on the local network. Streaming from the Internet may also show some improvement, but is mainly dependent on the download speed provided by your ISP and current Internet traffic conditions.

Posted on Aug 10, 2013 12:46 PM

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dblum

Q: Looking for help to improve Airport performance over LAN (WAN is fine)

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  • Helpful answers

  • by Tesserax,Helpful

    Tesserax Tesserax Aug 10, 2013 10:09 AM in response to dblum
    Level 9 (54,906 points)
    Wireless
    Aug 10, 2013 10:09 AM in response to dblum

    The one area you didn't mention is placement of your base stations as this can make all the difference for bandwidth performance. As you are already aware the "extend a network" feature with the 802.11n AirPorts works in sort of a wheel analogy. That is, the base station to be extended would be at the hub of that wheel and the extending AirPorts would be along one of the wheel's spokes. Daisy-chaining base stations is not allowed and is only available in the older 802.11g WDS configuration.

     

    With that said, please check out the following AirPort User Tip for details on how to be place your extending base stations to see if this helps.

  • by dblum,

    dblum dblum Aug 10, 2013 12:19 PM in response to Tesserax
    Level 1 (0 points)
    Aug 10, 2013 12:19 PM in response to Tesserax

    Hey Tesserax, I think you may be onto the problem. Of the 3 base stations, two of the 5GHz access points have good SNR (30 and 34 dB respectively) but  is  just 17 dB (its one of "spokes", not the hub). I wonder if one of my audio system components is interfering, e.g. an amp? I'll see if I can track down the source of the interference. As far as moving it, my only constraint is the ethernet cable linking it to its streaming device, and I suppose I can always buy a long ethernet cable to give myself more freedom to place the basestation in a place with low interference.

     

    Thanks for steering me in the right direction!

  • by dblum,

    dblum dblum Aug 10, 2013 12:33 PM in response to Tesserax
    Level 1 (0 points)
    Aug 10, 2013 12:33 PM in response to Tesserax

    One quick question -- I realized after taking the previous measurements using Apple's wireless diagnostic utility that those SNR readings represented the signal strength and noise associated with each basestation at the spot where I was sitting  with my Macbook Pro. But I need to know the SNR that each of the spoke basestations gets looking at the hub basestation, right? If so, how do I find that? Is the best way for me to place my MBP right next to each of the two spokes and read off the signal and noise measurements associated with the hub at each of those spots? Is there a way to pull this information directly off each of the two hubs? Or, am I interested in other measurements?

  • by Tesserax,

    Tesserax Tesserax Aug 10, 2013 12:37 PM in response to dblum
    Level 9 (54,906 points)
    Wireless
    Aug 10, 2013 12:37 PM in response to dblum

    I realized after taking the previous measurements using Apple's wireless diagnostic utility that those SNR readings represented the signal strength and noise associated with each basestation at the spot where I was sitting  with my Macbook Pro. But I need to know the SNR that each of the spoke basestations gets looking at the hub basestation, right? If so, how do I find that?

    That is correct. The simpliest way would be to temporarily power-down each of the extending base stations and just take the SNR readings of the "main" base station with your MBP at each of the extending base station locations.

  • by dblum,

    dblum dblum Aug 10, 2013 12:41 PM in response to dblum
    Level 1 (0 points)
    Aug 10, 2013 12:41 PM in response to dblum

    Assuming that the measurements I'm interested in are the signal strengthand noise associated with the hub when my MBP is placed next to each of the two spokes, for one it's -75 signal / -92 noise (ie 17 dB SNR) and for the other it's -66 / -92 (ie 26 dB SNR). So it would appear that one of the spokes is having a real hard time hearing the hub.

     

    So, I'll take some measurements around the room and find a spot that gets better reception. But in the mean time, can you explain why it is that this would affect LAN performance so much but not internet download performance? The device that's connected to the spoke that's seeing 17 dB SNR routinely gets download speeds between 10 and 20 Mbps from the internet.

  • by Tesserax,Solvedanswer

    Tesserax Tesserax Aug 10, 2013 12:46 PM in response to dblum
    Level 9 (54,906 points)
    Wireless
    Aug 10, 2013 12:46 PM in response to dblum

    Most Internet speed test utilities measure the overall bandwidth between the target server and your network client. As you are aware the local network is just one component of that overall bandwidth score.

     

    I would expect that any bandwidth performance issues on any of these components would affect the overall score. Where you will potentially see the best performance in improving the local wireless network bandwidth is for file transfers, streaming, etc. between devices on the local network. Streaming from the Internet may also show some improvement, but is mainly dependent on the download speed provided by your ISP and current Internet traffic conditions.

  • by dblum,

    dblum dblum Aug 10, 2013 12:55 PM in response to Tesserax
    Level 1 (0 points)
    Aug 10, 2013 12:55 PM in response to Tesserax

    Ok, cool. I'm really glad that the issue has been isolated. Thanks a ton for your insight!

     

    Hopefully I can find a spot where the signal strength of the hub is noticably better but that isn't too inconvenient for an ethernet run. My Sony BDP, which is the device connected to the problem basestation, has wifi capability, so I could always ditch the ethernet cable if the best spot for the basestation doesn't permit a cable run. But I'm aware that ethernet usually offers faster transfer speeds than wifi. Moreover, I'm not sure that the Sony BDP supports 5GHz. It might be a 2.4GHz-only device, in which case I'll have new interference issues to contend with, since like I said in my original post, there are several other 2.4GHz networks in my building.

     

    Anyhow, now that I understand the problem, I can figure out a solution. Thanks again.

  • by Tesserax,

    Tesserax Tesserax Aug 10, 2013 12:59 PM in response to dblum
    Level 9 (54,906 points)
    Wireless
    Aug 10, 2013 12:59 PM in response to dblum

    FWIW. I find that the best overall solution for wireless bandwidth performance is to use a "roaming" network configuration. But it would require Ethernet connections between base stations which isn't always practical or possible.

     

    The advantage of this type of network is that you can add base stations where you need them without the bandwidth loss of an extended network.

  • by dblum,

    dblum dblum Aug 10, 2013 1:11 PM in response to Tesserax
    Level 1 (0 points)
    Aug 10, 2013 1:11 PM in response to Tesserax

    Unfortunately that's not really practical for me based on where the Verizon FIOS installer decided to install my FIOS box. His suggestion seemed like a good, unobtrusive spot at the time, but in hindsight I should have had him run the line for the box to a more central spot on my apartment.