Why slow broadband on one computer but not other?

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jonathan18

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#56578 18-Jan-2010 09:14

Hi there

I've just set up our Slingshot broadband and was somewhat surprised at the speed - eg basic webpages took a number of seconds to load. I elected for the FS down/128k up package, however Speedtest showed our connection at around 2.27MB down/0.14 MB up. I spoke to someone at the Slingshot call desk who suggested trying another PC, which I did. The results were surprising, with the other computer showing speeds of between 5 and 6MB/sec, while the original computer being no faster than about 2.5MB/sec. (Eg. tests done directly after one another showed download speeds of 2.0 and 6.0MB/sec respectively).

I have tried closing down both antivirus and firewall applications on the slow computer, on the advice of the helpdesk, but this makes no difference to the speeds.

Can anyone offer me any suggestions as to what could be causing this discrepency and what I can do to fix it?

The "slow" computer is running XP; the "fast" Windows 7. I have had no problems earlier with differences in speed, although that was on TC cable.

Any help greatly appreciated.

Cheers
Jonathan

vexxxboy

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#290805 18-Jan-2010 09:21

what are your specs on each PC?,

Common sense is not as common as you think.

jonathan18

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#290811 18-Jan-2010 09:41

"Slow" laptop: Dell Inspiron 6400 / T2300 1.66 dual core / 2GB RAM / Windows XP
"Fast" netbook: Asus Eee 1005HA / 1.66 Atom / 2GB RAM / Windows 7 (so certainly not a grunty computer!)

What confuses me is that I never had this issue with TC cable.

Have not tried the connection speed of the Mac Mini but could do so if this would shed any further light on the situation.

cyril7

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#290814 18-Jan-2010 09:54

Hi, what is the MTU setting in your modem, it should be 1500 on a PPPoA connection, I seem to remember the Dynalinks default to that but just check, but I suggest the issue is more likely a TCP windowing issue rather than pure CPU power.

Cyril

sbiddle

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#290815 18-Jan-2010 09:55

First off your plan is limiting you to 128kbps upstream. This limits your downstream speed sognificantly, you really should be on a FS/FS plan if you want better speeds.

I'd place doubt on the 5-6Mbps download figures from the 2nd PC and suspect the test isn't giving true results, the maximum speed you should be able to get with a 128kbps upstream connection is around 4Mbps.

What type of modem/router are you using?

rscole86

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#290816 18-Jan-2010 09:56

Have you plugged both PC's into your modem/router via cable and not wireless?

Have you tried having them plugged it one at a time, into the same port, and seeing what the results are then?

Have you tried the TCP optimizer from speedguide.net for your XP machine?

cyril7

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#290820 18-Jan-2010 10:14

I'd place doubt on the 5-6Mbps download figures from the 2nd PC and suspect the test isn't giving true results, the maximum speed you should be able to get with a 128kbps upstream connection is around 4Mbps.

Hi, I would have to disagree there, you have to factor in latency, and from my experience it is quite common to readily get between 5-6Mb/s on a 128k uplink if the latency is relatively low, and using standard XP TCP stack setup. That said figures in the 4-5Mb/s are more common but to exceed this out to 6Mb/s is not uncommon.

Just to also reiterrate Ross's comment, do all checks via cabled connections, WiFi even if a solid 54Mb/s connection will give you unreliable throughputs.

Cyril

jonathan18

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#290835 18-Jan-2010 11:11

Thanks for all the replies. In reply to the comments/suggestions:

MTU ? yep, it?s set to 1500

Yep, I do understand about the limitations as a result of a slower upload speed; I am likely to increase to a FS/FS plan soon, but wanted to get things established (we have just moved, so there are costs associated with switching to Slingshot for all things ICT). However, that doesn't explain the discrepency between the two computers. I guess you're right that I could being given a false reading on the second PC, though how to determine that?

Modem is Dynalink RTA1320; using Belkin F5D7230-4 router (as per this thread: http://www.geekzone.co.nz/forums.asp?forumid=49&topicid=55723)

I have now tried connecting both PCs through the same port and run the tests: still get the difference of 2.06 versus 6.61 MB/sec.

LATEST: have followed the suggestion of running the TCP Optimizer on the XP machine, and eureka! I am now getting download speeds of 4.7 (Chch), 5.73 (Auckland) 6.1 (Napier), 7.23 (Wellington).

I wonder if this was caused by me running a similar TCP optimiser programme on this PC when we had cable broadband, and therefore it was set up to operate poorly through ADSL ? does that make sense?

Anyway, thanks everyone for the suggestions ? looks like things are working properly now! Though it would be good to know whether these are ?real world? speeds (as Cyril suggests are possible even with 128kb upload) or may not be correct (sbiddle?s view) - what's the best way to determine that?

Cheers
Jonathan

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Athlonite

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#291692 21-Jan-2010 04:30

try a real world download like the DirectX redist package from MS it's an 103MB so should give a better reading than speedtest.net

and yes cable is rather different in the way it uses the tcp stack rwin settings so the settings on the xp machine probably just needed to be set back to standard