Really hoping some DSL exports or even lurking BT engineers get to see this...
In summary I have frequent losses of sync on my line. My line is an average distance from the exchange (not sure exactly) and line attenuation is always pegged at 39.6 down and 22.1 up. The SPEED of my connection is fine, normally ~10mb, but can reduce to ~6mb if DLM kicks in due to frequent drop-outs.
Things tried so far:
- BT MK3 Faceplate
- 2x different modems, exactly the same behaviour.
- Disconnection of internal telephone wiring past master socket (I don't use it anyway)
- Changed twisted pair to property
- Changed twisted pair from cabinet
- Changed twisted pair from exchange to cabinet
- Visual inspection of exchange port and changed what is possible without a full lift and shift.
- Messing around with an AM radio set to 612Khz MW, nothing abnormal at my property.
- No REIN detected by Openreach on the line.
- Quiet line test is always perfectly quiet, even when internet is disruptive. Using the phone/etc has NO impact on my broadband.
Attached is a detailed graph of a 'typical' day. The data is gathered from a D-Link DSL320-B and I have not used routerstats due to it not properly supporting Linux (Wine is not Linux support).
>> Main Graph
A series of purple crosses marks a blackout. A single purple cross is not a blackout, its just that my computer failed to hit its test page once. There is one blackout (a big one where DLM adjusted my SNR margin) that is not "shown" on the graph but it happened.
SNR margin scale on the left
HEC errors scale on the right
HEC errors corrospond to DOWNSTREAM HEC errors, UPSTREAM HEC errors is always pegged at 0.
What this tells me:
- It isn't a HAM radio operator. Infact it isn't any sort of REIN or SHINE. There are no sudden or major drops in SNR margin.....
- ... however SNR margin does seem to drop SLIGHTLY for a while before a drop-out. This should not cause an issue on the 9db profile as it never went below 8db, but still died in a big HEC error-y mess.
Dropout 1: Graph Dropout 1
SNR margin gets a tiny bit worse before the big drop. HEC errors begin rising.
Dropout 2: Graph Dropout 2
SNR margin gets dangerously low all evening, again HEC errors start to rise and finally bang. This time DLM decides to move me from 6db to 9db.
Dropous overnight: Graph Overnight Drops
Loads of dropouts throughout the night, the SNR margin seems 1DB down from target during the unreliability but it IS still at 8db which is more than enough! After the re-sync at 07:15 AM the SNR margin seems more consistent and connection reliable.
I must re-iterate that even though there seems to be a slight link with SNR margin and drops, the SNR margin is NOT below spec (on the 9db profile at least) and is NOT dropping like a stone, only a tiny bit here and there.
... so, any ideas??? For the record, my ISP is working with me on this (thank god) but they are getting stumped now. They are offering a lift and shift next but I want to be sure my graphs correspond to a broken DSLAM port before going ahead with days of downtime.