I reset the stats, and after about 15 minutes the errors are at 65504, which I presume is the max it can count.
Mode: ADSL2 PLUS
Type: ANNEX_A
Status: Showtime
Downstream Upstream
Rate (Kbps): 14332 kbps 888 kbps
SNR Margin (dB): 14.1 10.3
Attenuation (dB): 9.6 5.5
Output Power (dBm): 0.0 10.0
Super Frames: 52607 52607
RS Correctable Errors: 16 0
RS Uncorrectable Errors: 0 65504
HEC Errors: 0 0
Total Cells: 238142 607446
Data Cells: 1417816 607433
Bit Errors: 0 0
Your downstream Noise Margin looks high to me, so I'm wondering if you hear any cracking / noise on the phone line (you need to used a wired handset for this as DECT phones may create their own noise)? Ideally you should run this from the test socket behind your BT Master Socket faceplate (take out the two screws and gently pull the faceplate forward.. making sure not to lose any of the small coloured wires that might be connected to it).
Once you have your telephone connected to the BT test socket dial 17070 for the line test facility and choose option 2 from the menu presented ("Quiet Line Test"). If you hear any line noise like cracking, buzzing etc. then something is causing interference.
Out of interest, is your master socket using a filtered faceplate? Do you know?
I don't have a landline phone.
I'm on ADSL. About eight months ago I had a lot of dropouts, periods of 3 minutes with no connection at all. BT sent a guy and he replaced some wiring outside of my flat and that seemed to fix the dropouts.
Is it worth calling BT about this? If I switch to a different ISP, would I have the same problems? I would guess so as it seems to be a line problem.
Getting BT to send out a man was quite difficult as you have to spend an hour talking to low level techs that keep asking you to reboot your modem. Any way around that?