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1 Computer unusable download speed; other OK

avisoft
Grafter
Posts: 45
Registered: 23-08-2007

1 Computer unusable download speed; other OK

I am trying to support a friend (on BT not PN) who has two computers connected to a router (Desktop via LAN connection, Laptop via wireless) and then to the internet, which have been working fine until 'about' 2 weeks ago.
From that time, the Laptop machine seems to be ok (MyBroadbandSpeed around 4-5Mbps), but the Desktop is so slow it rarely manages to even display the MyBroadbandSpeed web page! (or indeed any other pages) From other tests it seems Desktop upload speeds are as expected (around 47KBps) but download is slow and erratic (around 8KBps). I get the impression that it can download small files, but anything of any size it just hangs. This was first reported as a 'cannot download emails' type problem, but is obviously general, but NOT to do with the line, as it just affects the Desktop machine not the Laptop. They are both running up-to-date XP.
I saw suggestions the fix KB958687 may cause just these symptoms, and it was applied on 13/1. I removed it ... but XP added it back until I disabled AutoUpdates ... but removing it does not seem to have had any effect.
I have run out of ideas, apart from trying to measure speed between the Laptop and Desktop both ways.
Any suggestions as to what I could check next?
Thanks
17 REPLIES
Community Veteran
Posts: 1,850
Registered: 11-08-2007

Re: 1 Computer unusable download speed; other OK

perhaps it could do with a new ethernet card.  is the machine dirty inside?
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: 1 Computer unusable download speed; other OK

if there has bein no change in there setup then it does sound like hardware fault.
have you tried a diffrent ethernet cable?
they can fail but most ive sein just stop working not present slow throuput.
An obvious one and sry if it insults your intelligence are you sure nothing is using bandwidth in the background?.
avisoft
Grafter
Posts: 45
Registered: 23-08-2007

Re: 1 Computer unusable download speed; other OK

Difficult to see inside - it is 200 miles away and I am supporting it remotely! But I doubt it is dirty, from its age and location.
If it was the ethernet card would the upload speed be so much higher than the intermittant download speed? But I have wondered if I could/should update its driver - but that will be a last resort, as I do not fancy doing that remotely! (ie over the ethernet card ...)
Tomorrow I aim to try Laptop to/from Desktop speed tests, which may prove something!
There is nothing using bandwidth in the background - I am using NetMeter to see what is going and coming from each machine.
Thanks for the suggestions - keep them coming!
Community Veteran
Posts: 19,101
Thanks: 443
Fixes: 21
Registered: 31-08-2007

Re: 1 Computer unusable download speed; other OK

Is there another ethernet port on the router you could try, in case the one it's in has gone faulty?
PS. I can't recommend any specific robot arms to do that one remotely  Wink
grimme
Grafter
Posts: 241
Registered: 01-08-2007

Re: 1 Computer unusable download speed; other OK

Is the router one that is capable of setting bandwidth limits on each connection, and if so would it be possible that a low settng has been added for the desktop IP address or port?
Another possible thought - have the networking settings on either machine changed and something like internet sharing or bridging been added to either computer - this might  be making one machine go out onto the internet using the other one as a gateway.
I've come across a similar issue with sharing out a locally attached printer over the network also.
avisoft
Grafter
Posts: 45
Registered: 23-08-2007

Re: 1 Computer unusable download speed; other OK

Anotherone: Yes there are 4 ports, and I will get them to try another. I will also discover if the Laptop has an Ethernet port, and try using that on the cable normally used by the Desktop.
gimme: I can see no limits of any sort on the router for the Desktop or Laptop. It is not going through the Laptop, as it still works (just) when it is turned off.
Thanks for the thoughts. Investigations are continuing ...
Community Veteran
Posts: 26,686
Thanks: 910
Fixes: 10
Registered: 10-04-2007

Re: 1 Computer unusable download speed; other OK

Something you can do remotely: if the MTU on the router is not 1500 try setting it to that and see if it makes a difference.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
avisoft
Grafter
Posts: 45
Registered: 23-08-2007

Re: 1 Computer unusable download speed; other OK

I have now managed to do some tests tranferring 10 x 2MB files between Desktop and Laptop machines, using Windows move and NetMeter to observe throughput.
From Desktop to Laptop: about 1.6MB/s, taking about 15 seconds.
From Laptop to Desktop: varied erratically from 0 to 50 KB/s, and took about 40 minutes.
This shows it is nothing to do with the WAN side of the Router, but the problem must be the Desktop LAN card or software, or the Router LAN interface port (or software), and it only affects data entering the Desktop machine not leaving it.
When I can get the cables swapped I will try the Laptop on the LAN cable. If that works it MUST be the Desktop machine somehow.
@jelv: As far as I can see the router MTU is set to Auto, and it is actually using 1472 (by experiment with ping).
Thanks 
Community Veteran
Posts: 26,686
Thanks: 910
Fixes: 10
Registered: 10-04-2007

Re: 1 Computer unusable download speed; other OK

In view of what you've just posted I think there's more of a chance that setting it explicitly to 1500 might make a difference.
Edit: How did you determine the 1472? If using ping -f -l you have to add 28 to the maximum value of l to get the MTU.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
grimme
Grafter
Posts: 241
Registered: 01-08-2007

Re: 1 Computer unusable download speed; other OK

In the Properties of the Network Adaptor, there will be an advanced setting that shows the speed at which the card runs - usually it is set to auto, but sometimes can be FullDuplex or Half Duplex - it can be changed to FullDuplex to make sure that it always operates at maximum throughput.
Also, it might be worthwhile seeing if there are any driver updates available for the network card that mention specifically fixes for slow throughput. 
avisoft
Grafter
Posts: 45
Registered: 23-08-2007

Re: 1 Computer unusable download speed; other OK

@jelv: In that case the MTU is 1500 - I did not add on the 28. Sorry.
@grimme: It seems to be a 'SiS 900 PCI Fast Ethernet' card, and when I select Advanced Properties it has 'media Type' of Auto_Config. How do I tell what it is actually running at? One option is 100BaseTX Full Duplex, so I could try that. The driver is 1.16.0.0 dated 10/07/2002, and I beleive there is a 1.19.0.0 dated 29/6/2006, but I have not yet found any description of changes, and I have not dared try it yet (local driver updates give me the shudders, but doing them remotely - over the driver being updated - is scary!) However, I will investigate it further.
avisoft
Grafter
Posts: 45
Registered: 23-08-2007

Re: 1 Computer unusable download speed; other OK

I have now managed to test
(a) the Desktop in another router port - no change,
(b) Laptop connected to cable normally used for Desktop - Laptop exhibits the same slowness as the Desktop did!
This seems to show that the problem is either with the LAN cable, or the Ethernet part of the router.
Is my logic sound?
Community Veteran
Posts: 19,101
Thanks: 443
Fixes: 21
Registered: 31-08-2007

Re: 1 Computer unusable download speed; other OK

It seems to be, try another ethernet cable. If the problem is the same do a router reset, still the same, check all the settings make sure you haven't anything daft set. Still the same, borrow another router  to try.
avisoft
Grafter
Posts: 45
Registered: 23-08-2007

Re: 1 Computer unusable download speed; other OK

Thanks Anotherone. I have been wondering how best to get another router cable 200 miles away! A router reset will give me real problems, as I need some connection (however slow) so I can remote control the computer!