Upload speed degrading faster than download speed?

Discussion in 'Broadband' started by chris, Nov 19, 2012.

  1. chris

    chris Guest

    Hi all,

    I noticed this weekend that my upload speed degrades worse over wi-fi
    than my d/load speed. e.g. downstairs the speeds were measured (via
    speedtest.net) as ~10Mbps down and ~0.09Mbps up over wifi. Where
    upstairs when connected via ethernet I get ~12Mbps down and ~0.3Mbps up.

    Anyone any idea why the upload speeds are so much worse downstairs? BTW
    I'm on ADSL2+ with plusnet.
    chris, Nov 19, 2012
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  2. weird.

    Can think of no logical explanation - unless you have a very very
    marginal wifi connection and 'noisy' neighbours.


    (in-ep-toc’-ra-cy) – a system of government where the least capable to
    lead are elected by the least capable of producing, and where the
    members of society least likely to sustain themselves or succeed, are
    rewarded with goods and services paid for by the confiscated wealth of a
    diminishing number of producers.
    The Natural Philosopher, Nov 19, 2012
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  3. Do you measure speed with the same computer upstairs and downstairs?

    When you make the measurement, are there any other devices (computers,
    smartphones, game boxes etc) connected at the same time?

    When you check the speed by ethernet, do you switch off the wireless
    function in the computer?

    Can you check the DHCP client list in your modem/router, i.e. how many
    devices are connected? Is it one of the ones with a light that flickers
    when data is passing through (e.g. Netgear)? If so, does the light
    continue to flicker when you disconnect all your devices?

    If you only have one computer, can you borrow another one to test?

    The fact that you're getting 12Mb/s downstream suggests it isn't a line
    fault. Upstream should be about 1Mb/s, so if you're getting a lot less
    than this, even by ethernet, maybe something else is using it. Have you
    ever used a torrent type filesharing service for example.

    Roderick Stewart, Nov 19, 2012
  4. chris

    Martin Brown Guest

    The wired uplink speed is suspiciously low. I get better than that on
    basic ADSL2 so I suspect something is stealing your uplink bandwidth and
    bittorrent filesharing or something darker sending out spam.

    What speed does Wifi used upstairs or very near the router manage?

    Shutdown all other Wifi devices and retry. And/or do a deep AV scan.
    Martin Brown, Nov 19, 2012
  5. chris

    chris Guest

    No, different ones.
    Probably, but likely idle. I guess it could be other devices using the
    upload bandwidth. I'll try again more carefully.
    It's a desktop with no wireless.
    Good question. Don't know.
    Yeah, I don't think it's a line fault either.
    Upstream has never been near 1Mbps - I think it connects at 448kbps.
    chris, Nov 19, 2012
  6. chris

    chris Guest

    I'm not sure it's that insidious. My upload speed was typically ~400kbps
    when on ADSLMax and it didn't really change on ADSL2+. I don't I have
    Annexe M (or whatever it's called) implemented on my line.
    Good suggestions. I'll them out. Although, I don't think AV is relevant
    as the desktops are up-to-date Linux boxes and the Mac laptop is rarely on.
    chris, Nov 19, 2012
  7. If the modem upstream sync speed really is only 448kb/s but you're on
    ADSL2+ getting 12Mb/s downstream, then the first thing I'd want to
    check is the modem settings, and if possible try a different modem.
    Then I'd get on to Plusnet tech support. Your upload speed may be
    capped at a default provisioning level so you may need to request it to
    be changed. You should expect around 1Mb/s, maybe a little more. It's
    usually about a tenth of the downstream speed.

    You may have a wireless issue as well, but I'd get the basic connection
    sorted first. Then check if your wireless router and wireless devices
    are wireless n or g, and use a survey program like InSSIDer to check if
    anybody nearby is using the same channel.

    Roderick Stewart, Nov 19, 2012
  8. We're probably capping your upstream at the wholesale level. If you can
    provide me with your account username or a recent support ticket
    reference from your account then I'll uncap it for you?
    Have you tried alternating between wireless channels (1, 6 & 11) to see
    if any of them offer an improvement?
    Plusnet Support Team, Nov 21, 2012
  9. chris

    chris Guest

    You should have mail.
    chris, Nov 25, 2012
  10. chris

    chris Guest

    So, I've tried a few things this weekend:

    - moved the laptop to nearer the router (upload still ~0.1Mbps)
    - disabled all other wireless devices (still ~0.1Mbps)
    - tried different wireless channels (1,6,11 still ~0.1Mbps)
    - tried different speed tester sites (same)
    - connected laptop via ethernet to router (~0.3Mbps)
    - rsynced files wireless from desktop to laptop (speed ~33Mbps)

    It looks like the wifi upload speed to the internet is affected somehow,
    but intrinsic wifi speed is fine as is wired speed.

    However, I did notice in my router settings that the connection speed is
    888Kbps, but max speed is 448Kbps. I wonder if this is the 'wholesale'
    capping the Bob Pullen mentioned? I'll see if things change next week...
    chris, Nov 25, 2012
  11. At this stage, if you're getting these low internet speeds by wireless
    only, with several different wireless computers, I'd be suspicious of the
    modem/router itself. Is it wireless-g or wireless-n? In any case if it's
    the only thing you haven't changed, it's about the only thing left to try.
    Sometimes a factory reset and re-entering all the details can help, but if
    that doesn't do it, you need to beg borrow or steal another one.
    Undoubtedly it will be this. (And as I'm sure you realise it won't have any
    effect on the wireless speed, which is a separate issue).

    Roderick Stewart, Nov 26, 2012
  12. chris

    Graham J Guest

    I think this is an inherent limitation of WiFi.

    WiFi is a half-duplex system; only one end of a link can transmit at a
    time. By contrast Ethernet (over cat 5 cables) is full duplex; so both
    ends of a link can trasnmit simultaneously.

    Further, WiFi is a shared spectrum system; by contrast Ethernet over Cat
    5 cables provides multiple simultaneous connections from each endpoint
    to the network switch. WiFi is more like the 10base2 or 10base5
    ethernet which was a shared spectrum system, (CSMA/CD), except that
    whole packets are required to implement the collision detection mechanism.

    Further, TCP/IP packets are normally sent one at a time, and the next is
    not sent until the reply is received for the first packet (handshaking).

    What this means is that when using WiFi to upload to the internet,
    packets are sent first from the computer to the router, waiting for a
    handshake from the router. Each packet is surrounded by management
    packets that ensure no other wireless device is transmitting. The
    packet is then sent from the router to the remote location, again
    waiting for the handshake. Thus the transit time for the packet is the
    sum of the WiFi delay and the Internet delay. Your measured
    100kbits/sec is pretty fair. Adding a further WiFi connection using WDS
    or the like will halve the speed yet again.

    By contrast sending via Ethernet incurs a much smaller delay from the
    computer to the router (because it is a dedicated full-duplex channel
    operating at 100 Mbits - or 1Gbit - per second, with no overhead to
    manage any shared channel). Thus the the performance using Ethernet is
    effectively the same as the raw internet upload speed.

    This is aggravated by the use of other WiFi devices on the same network;
    and by WiFi devices on other networks creating interference.

    The only easy resolution is not to use WiFi. With the increasingly
    crowded WiFi spectrum I think WiFi is effectively dead. Ethernet cable
    is the only realistic resolution.

    Satellite systems suffer the same problem, but the packet transit time
    is often 400 milliseconds. So the satellite links operate a modified
    TCP/IP protocol where several packets are sent without waiting for
    replies; and the the replies when received are matched up against the
    sent packets.
    Graham J, Nov 26, 2012
  13. Er no.

    You need to learn about TCP/IP and window sizes.


    (in-ep-toc’-ra-cy) – a system of government where the least capable to
    lead are elected by the least capable of producing, and where the
    members of society least likely to sustain themselves or succeed, are
    rewarded with goods and services paid for by the confiscated wealth of a
    diminishing number of producers.
    The Natural Philosopher, Nov 26, 2012
  14. chris

    chris Guest

    Yes, I'm aware of that (and some of the rest, which is snipped).
    However, I would expect uploads and downloads to be affected equally (to
    a degree) by wifi problems. What I'm seeing is that wifi upload speeds
    are approx. 30% of the ethernet speed. Whereas download speeds are
    approx 85% of the ethernet speed.

    There's something that is adversely affecting uploads more than
    downloads. It could be that there's an overhead that translate as a
    ~100Kbps reduction is throughput in both directions. This is
    unnoticeable at ~10Mbps, but is significant at 300Kbps.
    chris, Nov 26, 2012
  15. [explanation of wi-fi follows]

    Apologies if I've misunderstood which bit you think is a limitation of
    wireless, but the max speed being 448 with a sync speed of 888 absolutely
    isn't. The OP has said that he gets this without wireless anyway. Speed is
    being limited somewhere else, almost certainly by Plusnet, as they have a
    default provisioning limit of 448 which you have to request to be lifted.

    There does appear to be a wireless issue as well. Accepting that wireless
    can never be as good as ethernet, it shouldn't be running at a fraction of
    1Mb/s. A good wireless-n router and appropriate wireless adaptors in the
    computers should be able to manage a lot better than that.

    Since moving my modem/router close to the phone cable entry in my hallway to
    investigate a problem (something else and now fixed), all my devices now
    connect by wireless as it would be awkward to run an ethernet cable, but
    performance is so good I probably won't bother. My main computer and printer
    connect through an ethernet wireless bridge on my desk where the
    modem/router used to be, and the internet speeds I'm getting (about 10Mb/s)
    are higher than before, I assume because the speed was previously being
    affected more by the long phone cable run than it now is by the wireless
    link. So wireless is not ideal but it can be useful. I don't know if speeds
    of 300Mb/s are really achievable, but you can certainly get a lot faster
    than any ADSL connection.

    Roderick Stewart, Nov 26, 2012
  16. chris

    Graham J Guest

    You are of course right. However, with large packet and small window
    sizes throughput can be disproportionately affected by occasional
    errors. But it probably doesn't make a big contribution to speed

    I suspect a much bigger contribution is caused by the overheads required
    to cope with the shared spectrum of WiFi.

    An example of this:

    At A there is a wireless ADSL router
    At B an access point
    At C an access point

    All three use WDS. A cannot communicate with C because the disance is
    too great, so B is placed midway between them and operates as a repeater.

    There is a computer at each location. The computers at A and C can
    transfer files at a reasonable rate - up to about 10 mbits/sec.

    The computer at A achieves internet downloads at 2 mbits/sec - that is
    what the ADSL service achieves at this location.

    The computer at B achieves internet downloads at about 1.8 mbits/sec; so
    the overhead for one wireless hop does not cause much degradation.

    But a computer at C only achieves about 1 mbit/sec internet download.

    Clearly a packet from A is received at B, then re-transmitted to C. The
    window size is supposed to be adjusted dynamically to cope with this,
    but clearly it doesn't.


    Has anybody else measured WiFi and seen the same degradation that the OP
    describes as affecting upload to a greater extend than download?

    Certainly wherever I have measured up and down speeds they have always
    been worse using WiFi or Ethernet over mains (which is of course a
    similar system) when compared with Ethernet using cat 5 cable - and if
    the internet connection is already marginal the additional delay
    interposed by WiFi makes the system unuseable.
    Graham J, Nov 26, 2012
  17. [...]

    I think the OP's system is a lot simpler than this, just an ADSL wireless
    modem/router with one computer connected by ethernet and another by
    wireless. I think the modem/router is possibly broken, or might benefit
    from a factory reset.
    No. Unless there's some other factor that he hasn't mentioned, e.g. he
    lives in a 4 storey mansion or the laptop is in a shed at the bottom of the
    garden, I think his wireless router may need attention, or replacing. On my
    system, speedtest.net shows about 10Mb/s down and 1Mb/s up, close to the
    sync speeds shown in the router config. I've measured these speeds on my
    main PC connected by an Edimax wireless bridge, a media centre connected by
    a Netgear wireless bridge, a netbook with a wireless-g adaptor running
    Windows XP and Ubuntu, another PC running Ubuntu with a wireless-n adaptor,
    and a Galaxy smartphone. They all work just fine, so it can be done.

    Roderick Stewart, Nov 26, 2012
  18. chris

    chris Guest

    Just noticed that your email address is unmonitored.

    I've raised a ticket, number 62739518
    chris, Nov 27, 2012
  19. chris

    chris Guest

    So a conclusion.

    It was a wholesale cap issue. I'm now connected at 888Kbps up and my
    ethernet-connected desktop gets a measured upload of 800Kbps whereas
    wireless devices are nearer 700Kbps.

    So kudos to plusnet for responding so quickly (ticket submitted Tuesday
    night, yesterday got confirmation of uncapping and getting improvement

    However, shame that the cap was there in the first place. Why don't they
    do this by default...?

    Thanks to all for your contributions.
    chris, Nov 29, 2012
  20. I'm not speaking for Plusnet, but I think the general reason for capping
    new internet installs at low speeds by default is in case the line is not
    capable of higher ones, so they need to prove the line quality by trying it
    for a while. Something like learning to walk before you try to run.

    As for why they don't *uncap* it by default once a consistent sync speed
    has been achieved, you'd have to ask the individual ISPs. Sometimes you
    have to request it, sometimes you don't.

    Roderick Stewart, Nov 29, 2012
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