downloading torrents kills any other internet use (on one machine only)

Discussion in 'Mac Basics and Help' started by toypadlock, Dec 1, 2010.

  1. toypadlock macrumors member

    Joined:
    May 17, 2010
    Location:
    UK
    #1
    hi,

    so i just moved into a new house and we got a new 20mb cable connection, which is faster and more reliable than i've ever had before.

    HOWEVER, when downloading a torrent, no other internet based service on the mac works (although other machines on the network are unaffected). it's only when downloading, and it doesn't matter how fast it's doing it (can be as low as 7kbps) and when it's just seeding it's fine.

    so i'm really baffled. am using transmission with connections set to a really low max and quite struct upload limits, so i have no idea what's doing this! oh, and i have a powerful iMac from late 2007 which always worked fine on torrents before, but can be a bit temperamental.

    thanks in advance.
     
  2. Makosuke macrumors 603

    Joined:
    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #2
    Sounds like one of two things:

    Most obvious and most likely, the UPLOAD speed is set too high on that machine; when you max out the upload on your connection, NOTHING works properly (including downloading the torrent that's uploading). Use a site like SpeedTest.net to test the actual upload (and download) you're getting, then set the torrent client to those numbers minus, say, a 20% fudge factor to leave some extra.

    The other possibility, if the up/down limits are already acceptable, is that the problem machine is allowing too many simultaneous connections, and your router or modem is choking on it. Check the simultaneous connections allowed and try a lower number to see if that helps.
     
  3. appleguy123 macrumors 603

    appleguy123

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    #3
    I have this problem on my MBP pro. Above says that it could be my router? It's a cheap NetGear that my ISP provided. Is there any stock that theory?
    This happens even when uploading only 1 kbps. Here are my speedtest results.
    [​IMG]
     
  4. Makosuke macrumors 603

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    Aug 15, 2001
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    The Cool Part of CA, USA
    #4
    I'm going to assume you've already made sure that your up and down speeds are set a comfortable margin away from your actual up/down throughput, as shown by SpeedTest. If so, then there are other possible causes, but a flaky router is at least one possibility. I will note that that'll usually only happen when there's heavier traffic, and usually when a router crashes it completely crashes--the network dies completely until it gets turned off and back on.

    Another possibility in your case (this is less likely for the OP) is that your ISP does traffic shaping or some other kind of filtering. I ran into that with Cox, for example, and it essentially looked like BitTorrent speeds dropping to a few KB/s after a short while, although all other traffic seemed normal.

    Here's a recent thread with a lot of back and forth on possible causes of similar symptoms, although in this case it was much more likely to be faulty hardware, since the network was obviously dropping completely:

    http://forums.macrumors.com/showthread.php?t=1053022
     
  5. Consultant macrumors G5

    Consultant

    Joined:
    Jun 27, 2007
    #5
    Limit your upload speed to maximum 80% of your average max upload speed.

    Otherwise you'll drown out requests from other computers to the internet, and if web pages don't know you are requesting pages, then your internet stalls.
     
  6. toypadlock thread starter macrumors member

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    May 17, 2010
    Location:
    UK
    #6
    my upload is set to a max of 30kbps, which is much, much slower than the downloads I get.

    my router is the one that came with the ISP, I guess. but it is wirelessN so I assumed wasn't terrible.
     
  7. DiamondGCoupe macrumors 6502

    Joined:
    Nov 12, 2007
    #7
    Just fyi you get the best dl/ul speed's by setting your upload max to 50kb/sec. No higher, no lower. Trust me on this.

    Might want to invest in a better/newer router I have no lag playing SC2 while download torrent's at 1.2-2mb/sec.
     
  8. Makosuke macrumors 603

    Joined:
    Aug 15, 2001
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    #8
    If you actually wrote what you meant to say, then you may still have it configured wrong. Upload and download speeds have nothing to do with each other, and on most modern broadband connections upload is MUCH slower than download. I, for example, have 6Mbit download and 512kbit up, and I don't actually get either of those numbers.

    If you have your UPload speed in your torrent client set to a higher value that the actual upload speed your connection offers, then ALL traffic will stop working properly, up OR down. As Consultant said, if your upload is maxed out, then web browsers and even the torrent client itself have no spare room to ask for more stuff, and if they can't ask, they can't download.

    So even if you have, say, 10Mbit down, if you have 256kbit up (which is only 32KB/s theoretical max--remember that there are 8 bits in a Byte), and you have your torrent client set to, say, 35KB/s up, then NOTHING is going to work whenever the torrents are asking for more than about 26KB/s.

    Again, I'm going off of what you just wrote, maybe you've got it configured fine and I'm just misunderstanding. If not, though, you want to go to SpeedTest.net when you have nothing at all running and see what it tells you your actual upload and download speeds are. Then take those numbers, multiply them by 0.8 to give some overhead room, and plug those numbers into your torrent client. So if SpeedTest.net says you're getting 4000kbit down and 300kbit up, set your torrent client to 3200kbit down and 240kbit up (which, since Torrent apps almost always measure in KB rather than kbits, will be 400KB/s down and 30KB/s up).

    If you've already done this and it's still acting up, then maybe you've got a bum ISP, or possibly a bad router.

    Incidentally, if it's JUST torrents that run slowly and everything else is fine, you might make sure you've properly forwarded a port on your router to the computer running BT--you can find instructions on every Torrent client site, and if you don't do that you'll never get a functioning torrent download. Most modern clients will warn you if this isn't set right, though, and if your router supports UPnP your client can automatically configure it for you.

    I assume you meant 50KB/s, not kb (lowercase b is bit, uppercase B is Byte, by general convention), but either way that's going to depend entirely on what ISP you've got. If your upload is only 256kbit, then setting upload to 50KB/s will kill your internet connection entirely. I can say that for a fact with my connection at home, for example--I've seen it do that when I accidentally set it in that range.

    If, on the other hand, you live in Japan and have 10Mbit upload (not at all uncommon with a fiber optic connection there or elsewhere in Asia), 50KB/s is ridiculously slow--you could probably be uploading at 600KB/s, and I see peers out of Asia doing that all the time. Same goes if you're on a campus network--here at work we see about 7Mbit up, real world, so if I wanted to get fired I could comfortably seed at 700KB/s if I wanted.

    It all depends on the actual, real-world speed of your connection, hence the need for a SpeedTest.net check or similar.
     
  9. toypadlock thread starter macrumors member

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    May 17, 2010
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    UK
    #9
    thanks all for helping btw.

    my upload is pretty fast, a couple of meg i think (i have 20mb fibre optic cable), so i really think it's not the upload, especially as this is happening when it's not even uploading anything.

    and it's not just the torrents running slowly; the mere fact that i am running torrents stops me doing anything at all on the internet, whether they're downloading fast or slow.

    it also doesn't affect any other machine on the network (when mine can't access the internet, all the others still can), so it's not a bandwidth problem at all.

    i have a feeling it's something to do with ports and connections, but i don't know what.
     
  10. yetanotherdave macrumors 68000

    yetanotherdave

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    Apr 27, 2007
    Location:
    Bristol, England
    #10
    Are you on sky broadband? When I was on them I had the same, basically they throttle your connection if you use torrents. Since I switched to Be, problems gone.
     
  11. toypadlock thread starter macrumors member

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    May 17, 2010
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    UK
    #11
    nope, virgin cable. they do engage in some throttling, but the connection overall is fine, it's just on my machine, which there's no way they could do from their end.
     
  12. appleguy123 macrumors 603

    appleguy123

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    #12
    I have Charter, I don't know if they do or not. If they do, is there any fix for it? Charter is the only fast ISP in my area.
     
  13. coochiekuta macrumors 6502

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    here and there
    #13
    write your congressmen everyone and let em know to support net neutrality. :D

    or not. :D
     
  14. Makosuke macrumors 603

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    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #14
    Although there's no harm at all in double-checking your actual upstream throughput with SpeedTest.net or similar (it takes all of 30 seconds), that indeed doesn't sound like bandwidth issues, since that would (usually) kill everything on that internet connection, not just the one computer. And, like you said, if it was ISP throttling, it would affect everything on the network equally, unless the ISP is the one providing IP addresses for each computer, rather than a single shared external IP address and private internal ones (which is how 99.99% of home networks are set up, so that situation is highly unlikely).

    Which does narrow it down to something your BT client is doing to that particular computer, but I can't really think of what. If it were doing something like trying to operate on port 80 (and forwarding all port 80 traffic to that one machine via UPnP) that'd just kill the web on all the other systems, not the inverse. Likewise any traffic issues should affect everything on the network equally.

    ...unless that particular computer is wireless and has a very weak connection--if it's got a terrible connection you could be saturating its wireless connection even if there's extra available on your actual fiber optic pipe. You can see what System Profiler says about the connection or, again, do a speed test and see if you're getting abnormally bad performance from that computer.

    If it's wired, I'm kind of out of ideas. Failing to forward a BT port to it would cause awful BT performance, but that wouldn't affect anything else on the computer.
     
  15. keen-on-mac-1 macrumors member

    keen-on-mac-1

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    Aug 18, 2010
    #15
    What torrent program are you using ? Did you try to search on Google about that ?
     
  16. toypadlock thread starter macrumors member

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    May 17, 2010
    Location:
    UK
    #16
    i'm using transmission.

    after much mucking about, i tried disabling the automatic firewall on the router and it seems to have worked.
     

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