Surely I should get more than 0.93 broadband speed?

[#1]

I agree with OldJim. If your router is syncing much higher at the test socket with the extensions disabled, that indicates interference or issues with the extension wiring or a device connected to it (Sky, cordless telephones etc). If you leave your router  connected to the test socket (synced at 6.5MB) you'll see your throughput (download) speed increase over the next few days as your BT/PlusNet IP profile increases to match.
You said you put a microfilter on the Sky box and that could well have fixed the problem, but until your IP profile increases you will still only see 0.9MB download. So plug everything back in the way you want it (with the microfilter in the Sky box), check your sync speed in the router. If it stays the same (6.5ish MB) then the problem was the Sky box and the microfilter solved it, meaning within a few days your IP profile will increase along with your download speed). If it syncs at 900ish, then the issue probably isn't the Sky box and definitely a wiring or interference issue. Does that make sense? ie: Focus on sync speeds for now, not download speeds.

[#2]

Yes that does make sense, thank you all for your patience, I did not know that the profile needed to update, I wrongly thought I could plug back in, wait for the lights to come on, and just do a quick speed test.
I will do as you suggest, plug all back in, plus new filter on the sky box, and monitor for a few days.
I really appreciate the help thank you.

[#3]

No problem and good luck!
When you plug it all back in, just check your router page to see what your sync speed is. If it's around 5500+ down then it's safe to say the issue was with the Sky box and you should have your full speed within 3-5 days. Just don't turn off the router too often as the exchange will interpret that as a fault and knock your IP profile down further/again, try to keep it on as long as you can.  

[#4]

Quote from: kmw350

I wrongly thought I could plug back in, wait for the lights to come on, and just do a quick speed test.

In the old days that would never have worked.  These days, if you are on a modernised ADSL2+ telephone exchange that would work with most every ISP except Plusnet.
The thing to look for is whether the downstream sync rate changes and/or the downstream noise margin (SNR) changes when you reconfigure.  In your case it's possible that the equipment in the telephone exchange has got so fed up with the noise from your unfiltered Sky box that's it not going to forgive you in a hurry even when you fit a filter.  In which case you would need to ask Plusnet for a reset once you have sorted-out your wiring. 

[#5]

Lemmiwinks,
what you refer to as synch speed I presume is :
Link Information

Uptime: 0 days, 0:41:05
DSL Type: ITU-T G.992.1

Bandwidth (Up/Down) [kbps/kbps]: 960 / 3,552  
Data Transferred (Sent/Received) [MB/MB]: 2.25 / 6.41
Output Power (Up/Down) [dBm]: 12.3 / 19.3
Line Attenuation (Up/Down) [dB]: 21.0 / 36.0
SN Margin (Up/Down) [dB]: 11.0 / 15.3
System Vendor ID (Local/Remote): TMMB / ----
960 / 3,552 is better than it was before I plugged the filter in at the sky box, though I actually saw 6,000 plus at the test socket.
maybe my constant resetting and speed testing this afternoon has already caused the exchange to lower the bar to 3552? How would I get it raised back up again if this does happen?
Anyway, I will leave it now and see how it settles.
Thanks
Keith

[#6]

It looks like the exchange has set a target downstream noise margin of 15 (the default is 6 or 9). That will be considerably lowering your sync speed which should be 7000 or more for your attenuation. This is likely to be because of the exchange seeing the line as being unstable due to problems caused by the Sky box. If Plusnet see the line has been continually connected for two or three days with no issues they can request a SNR reset which will put the noise margin back down to the default and give you a much higher sync speed.

[#7]

Righto, I shall keep an eye on it and ask for the reset if appropriate, thanks

[#8]

Hi there,
If the current connection has been ongoing throughout the weekend we'll be happy to reset the SNR for you. Sorry for the wait, but it's important not to reset the SNR when the connection is dropping or it'll ruin the speeds and thresholds that are set when the line trains.

[#9]

Thank you Matt, here's hoping it runs consistently now for the weekend

[#10]

I have a further question - I am unable to check my IP profile, I keep getting an error if I try to use the ADSL & fibre to cabinet button, so I have only been able to use the 'up to 24mbps speed test beta' button to report my speed. Can anyone explain why I cannot use this?
I just keep getting the message
The Performance Tester is currently unable to run a speed test for your broadband connection. Please try again shortly, however if this problem persists, raise the issue with your service provider.
This has been the same all day.

[#11]

God knows - certainly we don't as that tester has a mind of its own,
However as you are on 21CN ADSL2+ it should automatically update following a change in sync speed.
The value is 88.2% of your sync speed
The part which doesn't update quickly is the Current Line Speed given here https://portal.plus.net/my.html?action=data_transfer_speed

[#12]

Jim
I'm sorry but that link is just taking me to the customer login screen for some reason. ..?

[#13]

You need to be logged in to the portal for that to work. Just log in and it will then continue to the correct place.

[#14]

Quote from: kmw350

I just keep getting the message The Performance Tester is currently unable to run a speed test for your broadband connection.

Try the new BT Wholesale test. Once you have (hopefully!) completed the first stage of the test, click on to "More diagnostics" and enter your phone number in the first box, leaving the rest blank, and then click Go. You'll then see "Sending results to server" and end up with the summary screen showing the speeds obtained and your IP profile.
Paste that info back here...

[#15]

OK, The link to my current line speed worked:
estimated line speed 'not recorded (service activated before we introduced estimates)
current line speed 1.
As for the BT Wholesale test:
Down 0.95
up 0.7
ping latency 115
Impressive figures I think you'll agree lol. I wish I was one of the people complaining about only 5 or 6 Mbps. (to be fair ping is normally lower, around 45, don't know why it's up just now).
But in the second part (further diagnostics), I input my phone number and it is still returning the same error - 'unable to run speed test for your connection etc'.