Current line speed vs sync speed

[#1]

Hi,
Despite my router generally syncing at around 3500 kbps, I've never had actual download speeds higher than around 1.8Mb. Looking at https://portal.plus.net/my.html?action=data_transfer_speed I see the current line speed says 2Mb, which is more like the real speed I'm seeing. What is this figure - the description makes it sound like it should be roughly the same as the sync speed, but it's much lower.
I know the data transfer speed will be lower than the sync speed, but I'm not sure why the connection speed listed on the PlusNet site is so much lower than the sync speed reported by the router.
Thanks,
James

[#2]

Do you know if you are on 20CN or 21CN?
What does the BT diagnostic speed test give as your IP Profile?
See http://community.plus.net/forum/index.php/topic,143835.0.html

[#3]

Hi,
Not sure if I'm on 20CN or 21CN, BT diagnostic says the following:
Download speedachieved during the test was - 4.42 Mbps
For your connection, the acceptable range of speeds is 0.6 Mbps-7.15 Mbps.
Additional Information:
Your DSL Connection Rate :3.46 Mbps(DOWN-STREAM), 0.45 Mbps(UP-STREAM)
IP Profile for your line is - 2.5 Mbps
dick:quote

[#4]

If it only gave the downstream IP Profile you are on 20CN (on 21CN it gives the profile for up and down).
The current line speed should match the IP Profile so you need to ask Plusnet to correct that.
Unfortunately the IP Profile on 20CN goes in steps - if you were to sync a little bit higher consistently you could move up to the next step - see http://www.kitz.co.uk/adsl/IPprofile.htm#IP_and_bRAS_profiles. A bit above that table it tells you how long it takes for the profile to change.