Why is my IP Profile half of what it was?

Question

So I signed up for the 20mb broadband service and had it activated 14 days ago.  On the day it was activated, I ran a speed test and my IP profile was over 19,000Kbps (indeed, before I upgraded, BT told me from their data I would be achieving 19mb).
Now my 10-day period is over, my IP profile has reduced to 11,400Kbps and my download speed is significantly lower than it was.
1. Best Effort Test:  -provides background information.
Download Speed
12420 Kbps
0 Kbps
21000 Kbps
Max Achievable Speed
 Download speedachieved during the test was - 12420 Kbps
 For your connection, the acceptable range of speedsis 2000-21000 Kbps.
 Additional Information:
 Your DSL Connection Rate :15348 Kbps(DOWN-STREAM), 1060 Kbps(UP-STREAM)
 IP Profile for your line is - 11400 Kbps
The throughput of Best Efforts (BE) classes achieved during the test is - 10.46:20.17:69.37 (SBE:NBEBE)
These figures represent the ratio while sententiously passing Sub BE, Normal BE and Priority BE marked traffic.
The results of this test will vary depending on the way your ISP has decided to use these traffic classes.
2. Assured Rate Test:  -provides background information.
Download Speed
8609 Kbps
0 Kbps
1600 Kbps
Max Achievable Speed
 Download speed achieved during the test was - 8609 Kbps
 For your connection, the acceptable range of speeds is 1536-1600 Kbps.
 Additional Information:
 Assured Rate IP profile on your line is - 1600 Kbps
Whilst I appreciate that this is much better than a lot of people are getting, I don't understand why it was so high at first, but now it's reduced by almost half, and my download speeds are 6,500Kbps slower than I was told my line would operate at (at 8am on a thursday so traffic is hardly an issue).
This is the dump from my Homehub:
ADSL line status
Connection Information
Line state
Connected
Connection time
0 days, 21:57:09
Downstream
15,348 Kbps
Upstream
1,060 Kbps
ADSL Settings
VPI/VCI
0/38
Type
PPPoA
Modulation
G.992.5 Annex A
Latency type
Interleaved
Noise margin (Down/Up)
14.9 dB / 6.3 dB
Line attenuation (Down/Up)
23.0 dB / 9.6 dB
Output power (Down/Up)
23.1 dBm / 1.6 dBm
Loss of Framing (Local/Remote)
0 / 0
Loss of Signal (Local/Remote)
0 / 0
Loss of Power (Local/Remote)
0 / 0
FEC Errors (Down/Up)
3789 / 0
CRC Errors (Down/Up)
96 / 0
HEC Errors (Down/Up)
706 / 0
Error Seconds (Local/Remote)
33 / 0

Answer 1

Hi there
In short, for your line attenuation on 21cn you should be looking at IP 16000 kbps.
Although presently your noise margin is running at 15db, and to achieve best speed and throughput it needs to be as close to 6db as possible.
There have been a lot of issues lately with 21cn, with latency and banded profiling ... although you don't seem to be in one ...  yet.
You could try connecting directly to the test socket, behind the faceplate, to see if the connection improves over the next few days .... you may have some internal noise issues to deal with.
Try it, and keep us posted.