Misleading Speed Advice

[#1]

It seems that Plusnet is economical with the truth, or one could even be inclined to put it stronger than that.
I have had problems with my broadband speed and my line will hold steady synchronisation with the exchange without dropping for days, weeks (and months) at a time and sync reliably at 5000 Kbits/s or greater, but I can never get download speeds greater than 2600 - 2700 KBits/s even at the quietest times of day or night.  The speeds are much worse, less than 1Mbit/s and down to 600 KBits in the evenings. 
I have followed all the instructions of the support team for over two weeks including "reboot now and you will benefit from the new profile" (as shown on their tests) but it has never produced any result except to give me an even better sync speed but a lower download speed for a while following the reboot. It soon recovers to consistently get stuck at 2.6 MBits again.  I have come to the conclusion that the max download speed has been artificially choked and restricted by Plusnet recently (but refusing to admit to it) even though the BT Speedtest says my line should be downloading at 4000 KBits with a sync of 5MBits.  Continuing to put out the pap of "reboot and you will be alright" without getting to the heart of the problem has infuriated me.  I might add that I do not use the bandwidth excessively by doing peer-to-peer downloads or anything similar.
I have been with Plusnet for a few years and previously used to recommend it but this has now seriously changed my view.

[#2]

Have a go at the advice on this page if you're using Xp.  If you're running Vista you can't change RWIN but you can adjust the MTU (there's a link on the page).
Tweaking your MTU and RWIN settings should get a bit more speed out of your connection (I use MTU = 1430 RWIN = 166800).

[#3]

It's highly unlikely to be PlusNet, unless there's a local, specific and undiagnosed problem.
There are overheads in any process, and you can excpect downloads to run, at best, at about 80% to 85% of your sync speed.
Please post your router stats so that we can advise.
Meanwhile, what Paul03 has advised is a definite step to take; incorrect MTU and RWIN settings become more and more important as speeds increase, certainly over 2meg and definitely as one approaches 8meg (or higher). Also your PC and hardware can slow things down if of a "below average" specification. Not to mention using wireless networks

[#4]

Hi Warmrain,
Given that the majority of the services that we provide are on monthly contracts, it's in our best interests to keep you happy.  I can certainly say that we wouldn't be economical with your speeds but merely applying the data as given to us by BT.
BT currently have an IP Profile set on your line of 3500Kbps, with your current sync speed of 4128Kbps.
Can you run a BT Speedtest to see what sort of throughput it gives you?
http://www.speedtester.bt.com
Useful reading: link:speed

[#5]

The MTU size set in the Router/Modem is 1458.
Hardware is a reasonably fast cpu at 2.8MHz running Win2000professional connected via a 100Mb ethernet wired connection.
The BT Speedtester does not complete as usual and crashes at "progress=96% complete stage" but download speeds through the Plusnet BB speedchecker are 2.3 - 2.4 MBits/s.
Some stats attached as pdf.

[#6]

Can you try using Internet Explorer for the BT Speedtester?
Many report more success using that.

[#7]

Quote

The MTU size set in the Router/Modem is 1458.

but what is your PC set at? that is more important than the router

[#8]

You may find this page helpful regarding RWIN: http://www.dslreports.com/tweaks/RWIN
Note that the Windows 2000 default (of 16K) is generally way too low for broadband.

[#9]

The MTU on your PC should be set to be the same or lower than that set on your router.  It'll take about 2 minutes and a reboot using DrTCP as described on Kitz's webpages.