DP = Distribution Point.
Not all poles have the actual distribution point which could actually be located a few poles away from the one you mention, or even possibly somewhere underground (e.g. in a chamber).
Having seen BT's Network Records for my connection & physically measuring the known route with a trundle wheel, I do know for certain that my connection is a little over 1000m to the DP from the FTTC cabinet plus around 40m from the DP to my master socket.
I do suspect that your connection is actually quite a bit more than 600m in total length from the cabinet, perhaps around 900m or so (or it does have a 'fault').
When DLM has been reset (following a number of engineer visits until physical line problems were eventually permanently fixed), my connection can sync at up to 35Mb, reducing to 27Mb or so after DLM eventually applies Interleaving etc.
Your 18Mb does seem quite low from the initial 37Mb, but you may be be suffering from poor condition cabling/joints etc.
If you are using a Huawei HG612 modem & are a Windows user, you could 'unlock' the modem to allow access to its stats & use the HG612 Modem Stats 1.0 suite of programs (available for free download here:-
HG612 Modem Stats 1.0) to monitor your connection stats as both snapshot current conditions and/or monitor ongoing stats 24/7.
That may highlight where the problem lies.
HG612 modems, both locked & already unlocked regularly appear on ebay, so if you wished to keep your existing HG612 in 'as installed' condition, you could use the spare one just for dtats gathering purposes.
If you were provided with an ECI modem (not impossible, but quite difficult to unlock & its stats are currently rather unreliable), an unlocked HG612 will still work on your connection.
Are your speeds checked wirelessly?
For a true reflection of your connection's performance, you would need to connect to the router/hub via ethernet cable.
Also, which Operating System are you using on the PC you use for speed testing?
It may help if you posted the results from the BT speed test at
http://speedtest.btwholesale.com/ (including the Further Diagnostics data that will also report your current IP Profile).
Edited by deleted (Sat 30-Mar-13 12:14:10)