Extension wiring should be daisy chained via the master socket, your extension wiring is a spur from the incoming cable and will be acting as an aerial to pick up noise or causing signal reflections both of which will interfere with the broadband signal.
Thanks Licquorice, understand you now!
Here are the stats:
BT Hub 6A
0 Days, 2 Hours 8 Minutes 34 Seconds
7.20 Mbps / 13.10 Mbps
14332 / 46640
10.7 dB / 21.8 dB
20546 MB Uploaded / 33124 MB Downloaded
With that wiring do you find that your broadband drops every time you make or receive a phone call the drops in internet connection are resulting in higher noise margin and lower speed. So sort out the star wiring and connection will start to improve
You could of course just disconnect the white wire which connects to extension and then just get cordless phones
I think what the plan will be is to remove the unwanted extensions, and only leave the one that is connected to the upstairs LJU box, until I get a local engineer out to replace the LJU.
Does this sound like an appropriate course of action?
Once you disconnect the white wire/cable then you have fixed the problem and connection will improve. Up to you if you want to upgrade the master socket
What does BT Broadband Availability Checker estimate for your phone number? Post just the whole table and the line above it, blanking out your phone number. If it doesn't recognise your phone number, use the Address Checker, not the Postcode Checker.