Please post your full Router Stats. For a Home Hub see on here: Broadband Top Tips . Full router stats are key to any speed & connection issues.
Try plugging your router into the hidden test socket that is revealed when you remove the bottom half of the split faceplate (2 screws) of your master socket. Only do this if you have a split faceplate. Do you have any extension sockets? Are there any wires connected to back of faceplate?
Post your full Router Stats when plugged into test socket.
Try the BT Quiet Line Test (dial 17070 Opt 2), preferably with a corded phone, in the test socket with the router disconnected. If there is any noise, report to your landline provider as a voice fault (don't mention Broadband). Often sorting out voice faults will fix the Broadband as well.
@Rich44 if this is correct 'Sync speed has dropped twice since 9am noise margin still 6dB' then you are dropping conenction as sync speed only changes on drop/reset whereas attainable/max speed will fluctuate without a reset