Recent drop in connection speeds

[#1]

I spent a few hours the other day trying out four of the ADSL routers I have. I think the upshot of this is that my connection speed has been seriously downgraded. Prior to this, my router would quite happily connect at a minimum 7k+, frequently higher than that. Now however, I get 4.5k and that's only the connection speed, the actual download is 3.5k.
Could my line be reset please so that it can 're-learn' what is a stable but higher connection speed?
Downstream Upstream

SNR Margin: 6.9         6.7 db

Line Attenuation:35.0         18.6 db

Data Rate:      4543         736 kbps

Max Rate: 10320         732 kbps

[#2]

Hi there,
No problem, I've submitted a line reset so you should start to see some improvement.
SNR resets can be as quick as a few minutes to take effect but can take up to 24 hours to go through, hope that helps.

[#3]

Hmm...not quite the result I was hoping for.  All those CRC errors in the space of about 40 minutes following reboot of router. There were thousands more than that following line reset, the router reboot was me being desperate.
              D/stream U/stream
SNR Margin : 6.6               8.5 db
Line Attenuation : 35       18.6 db
Data Rate : 6419       728 kbps
Max Rate : 8448       728 kbps
CRC         : 19721     65505

[#4]

Hmmm, it looks like the SNR reset hasn't taken effect.
I've submitted another one as a direct change to DLM.
Keep us posted.

[#5]

No change....

                      D/Stream U/Stream
SNR Margin         : 6.6                 8.5 db
Line Attenuation : 35                 18.6 db
Data Rate         : 6419         728 kbps
Max Rate       : 8476         728 kbps
CRC               : 42724         65504
I think the CRC count has wrapped round at least once

[#6]

Have I been forgotten???????????????
                                  D/Stream  U/Stream 
SNR Margin          :  6.6                  7.5  db
Line Attenuation  :  35                  18.7  db
Data Rate          :  7755                736  kbps
Max Rate          :  10576                732  kbps
CRC                  :  15054                  0 

It was stable for a while when SNR was a little hgher (can't remember exact figure) and the CRC errors were infrequent. However, IO switched the router off overnight a few nights ago and now I'm back to the above stats.
Why is it a big problem switching router off overnight?  I used to do it every night when I was with Talktalk and EE but with +net it seems to be an issue. Surely, BT or +net can detect the difference between a random disconnect and immediate re-connect attemt and a disconnect that is not followed by a re-connect for over 8 hours?

[#7]

The 4543 looked like a typical banded speed, but I didn't think the 6419 and 7755 were banded speeds. So I don't think there is anything particular limiting the speed.

[#8]

It's not really the speed that concerns me, it's the thousands and thousands of CRC errors