Filter fitted by engineer not working?

[#1]

We've recently had two engineer visits to fix a fault on our broadband.
The second engineer fitted a filter to our Master Socket. Since then, using the phone either disconnects our broadband connection or stops the internet from working for the duration of the call.
This happens with both the router supplied by Plusnet and our own Netgear router. We've also tried two different phones.
We removed the filter and tried three different plug-in filters, but the result was the same.
The line is also quite noisy, and our speed has dropped from 6.5Mb/s before the fault to less than 3Mb/s now.

[#2]

If you have a test socket can you try to connect into it?

[#3]

I've just connected the router directly to the test socket.
Tested three filters, making two phone calls each with a wired handset.
Each time the internet was disconnected (graph attached):

[#4]

Hi mwkv,
Welcome to the forums.
Looks like you are a savvy user - immediate recourse to RS is impressive.  I hope you are using the full version?  There is a link below which has some useful suggestions for configuring RS.  If you do not have the TG582n router, this might be a little different.
Sight of the SNRM plots would be useful please.
That said whilst there is noise on the line, trying to fix a BB issue is nearly futile.  You might want to raise a new phone line fault using the link below.  From what you wrote it is possible that there is nothing wrong with the filter, rather you just still have a bad line.
I once had a repair done and it was really first class... for 90 minutes and then the line went dead.  Due t the local wires being aluminium, the joint fractured shorty after being repaired. 

[#5]

I read about Router Stats on a forum and have been using it for the past week or so. The engineer who fitted the filter has told Plusnet that the problem may be at our end, so I've been trying to figure out what it might be:
"A historic LTB issue was identified. BTW Fault Localization Analysis indicates a potential Customer Domain issue. Please check 'Local Access Network' tab for more information."
Using the Router Stats log led to the discovery that the disconnections often occurred when using the phone line. As far as I know, this was not an issue before the fault first occurred in April, as before then the router would often show that the connection had been up for several days at a time.

[#6]

Hi,
Those RS plots are grim.  A number of points are note worthy.  A target SNRM of 9dB indicates the DLM has already acted to stabilise the line.  There are some reports of negative SNRM.  That is technically not possible, but I have seen routers report such figures. Which router are you using?  Do you have an alternate you can try please?  Personally I have found the PlusNET TG582n with the 10.2.2.B firmware to be excellent.  Mine has remained connected to a single xDSL session for over 320 days at a SNRM of 3dB.
Without also seeing the synch plot, I can only presume that the zero plot intervals are long attempts to resynch.
Having resynch'd the SNRM plots show repeated dreading slopes.  This indicates the presence of noise.  The subsequent resynch at a higher SNRM is I suspect an attempt by the. DLM to stabilise things - quite likely at a somewhat lower synch.
Sight of your router stats would be useful please.
Whilst you have noise on the line, you have a line fault.  End of.  BT engineers trying to duck difficult issues is sadly all too common.  The association of degradation during phone calls could point to a filter problem.  It could also point to a line splitter card issue in the exchange.

[#7]

The router used in those graphs was the Netgear DG834G v4. The spikes and flat lines coincide with the test phone calls I made.
I repeated the tests yesterday, using the Technicolor TG582n supplied by Plusnet, and the results were the same across eight phone calls, with both the filter fitted by the engineer, and then using the test socket with three different plug-in filters.
The last engineer said he could hear noise on the line and had traced the fault to a connection somewhere between us and the exchange.

[#8]

I'm really not sure why there's discussion about which version of RouterStats and wanting to see stats from the router, nor why the OP was asked if he'd tried the test socket - the information in the first post was quite clear, not only 3 filters tried, but 2 modem/routers and two phones. This is the 'key' information

Quote from: mwkv

The line is also quite noisy.............

If you are getting noise and crackles on the phone line, double check with a corded phone plugged direct into the test socket, then you need to report a phone line fault, not a broadband fault.
Filtered faceplates, different modem/routers etc will not fix an intermittent bad connection on the phone line.
Have you had any other issues with making outgoing calls or receiving calls other than noise? One of the more frequent is that the phone rings and then stops, but the caller is still there when you pick up the phone.