Hi razpag,
Thanks for your response.
Yes, I have previously synced at around 35 Mbps - from BT's speed tester:-
"Download speed achieved during the test was - 32359 Kbps
For your connection, the acceptable range of speeds is 22767-32525 Kbps .
Additional Information:
IP Profile for your line is -32525 Kbps"
I take it (maybe incorrectly) that an IP profile of 32525 Kbps comes from a sync speed of around 35000 Kbps (35 Mbps).
That was the sync speed the original installation engineer told me I had achieved.
Even if my understanding is incorrect, actual download speeds were between 32 & 33 Mbps.
Very briefly, what is a HR type fault?
1) By road it is around 0.5 mile. In a straight line it is much less (not relevant though). The line is at the very least 10 years old, probably quite a bit older. It does zig-zag quite a bit too.
Just for curiosity, if the line was indeed much longer than 0.5 mile (say a full mile due to the zig-zagging), could I have ever synced at 35 Mbps? I have seen a few charts, but they do appear to contradict each other somewhat.
2) A short while ago this morning, my ISP confirmed they will be taking no further action as my service is being delivered within specification. I wrote back with a long (very long) response, particularly mentioning the crackly phone line.
As my phone provision is also via my ISP as a phone / broadband bundle, I am not allowed to contact BT regarding line "faults".
3) I expected some speed fluctuations (contention, traffic management, condition of mainly overhead line being affected by temperature/rain etc.).
4) There has been no mention of a hard cap by my ISP.
Two days after the fault "repair", according to a report from my ISP, it was confirmed that Interleaving was automatically set at "HIGH" for the downstream & at "ON" for the upstream.
The report also confirmed Downstream Speed 12.857 Mbps, Upstream Speed 0.79800004 Mbps.
Since then, the BT modem has been replaced & my profile reset (only at 24 Mbps though).
Would Interleaving affect sync speeds, or just throughput speeds? The engineer who replaced the modem & organised the profile reset had never heard of Interleaving so couldn't comment.
He also said he couldn't check anything in the cabinet as he wasn't allowed to access cabinets.
Do BT engineers have differing access levels? The original installation engineer did struggle a bit to get me set up, flitting between my home & the cabinet, saying he eventually found a dodgy connection in the cabinet.
Would the profile reset have turned off any interleaving anyway?
From what I have read up on so far (elsewhere), it appears that profile speeds via FTTC are very quickly lowered following "faults", but can take much more than 10 days to recover (sometimes being stuck forever at the lower rates).
Unlike ADSL, ISPs (& remotely located BT staff???) apparently now have no control whatsoever over profile speeds / interleaving etc., having to rely entirely on the DLM in the cabinet itself?
So many questions from a newbie!!!
Don't worry, once I'm an "expert" I will give back my own "two penn'orth".
Paul.