On that attenuation I would expect well over 4Mbps, possibly over 5Mbps.
It would be useful to see a set of stats taken immediately after a reconnection.
You are right so say a move to another non-LLU would not sort things, but I doubt if LLU would do so properly either unless it is the BT exchange equipment at fault.
Re phone noise, if you disconnect all broadband equipment, then plug a phone into the master and try the quiet line test
. 17070 Option 2. Preferably use a corded phone not a DECT one.
If you have a definite noise on that test then report it to your phone provider
. Do not mention broadband
, just that there is noise on your phone line.
If an engineer has to visit to fix a noise fault he should fit a new NTE5 master socket to replace the old one you have and this should be free of charge.
If any noise fault gets fixed your broadband should improve a bit over the following few days and a lot over the next few weeks. Have a browse of the BT DLM, BT IP Profiles, Noise Margin and Troubleshooting sections of my website for a lot of explanation of how things work.
My broadband basic info/help site - www.robertos.me.uk
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