I've been with BT Infinity 2 since July 2013 and at first I used to get around 58 Mbps. Over the years this has dropped to 49 Mbps. Last October 2015 I noticed a sudden drop from 49 Mbps to 39 Mbps which I complained about but nothing was really done about it so just left it. I noticed from the line stats graphs there is increased noise.
Last Monday things have become worse. I noticed the SN margin fluctuating between 0 to 6 db and attainable rates from 30 Mbps to 18 Mbps then back up to around 38 Mbps. I could also near some static noises on the phone line, a recording is here: https://www.sendspace.com/file/22u6fb
I also noticed the following occurs:
The SN margin drops when:
-Landline is called (without any telephones connected)
-Landine is called (with telephones connected)
-Landline is picked up
This sudden SN margin drop causes errors which nearly drops the connection.
Below are some graphs from 30 September 2015 and today 9 March 2016
So now I've managed to schedule an engineer home visit, I'm just concerned I may be charged £130 but I'm certain there is nothing wrong at my end.
Does this look like a problem between the cabinet and the master socket?
Hi, yes, there is still static noise (you have to really listen carefully) even when connected to the test socket and also with another telephone.
Did you hear the recording I uploaded?
Do you think the engineer would be interested in seeing these graphs too to further support my case?
Engineer came and could not fix the fault at my end. He said the line card at the exchange might need replacing.
Why does the SN margin still drop when the phone is picked up? Sometimes it's enough to cause the FTTC connection to drop.
He said he goes by protocol and doesn't do more than the job required or he'll get scolded as previously.
I showed him some graph stats from my HG612 modem but again he said he can't do any more than test the line in that visit.
The line tested OK from the test socket but I still don't know why when the phone line is in use the SN margin drops disrupting the broadband connection.
It's as if the sudden burst of electricity when making a call causes interference with the VDSL2 signal.
As I've explained, something (unknown) is causing excess noise when the phone is in use. There could be a dodgy phone, dodgy filter, high resistance fault, a fault at the cabinet, or a fault at the exchange.
When this "noise" happens, it is interfering and causing problems with the frequencies that your broadband connection uses, interupting the packets of data causing errors. Too many errors in a short period of time will ultimately stop data transmission and cause the connection to drop.