Looks as though above 860 the attenuation is too high and there will be nothing available ... can you grab the HLog and QLN graphs too?

See QLN and HLog

It really does look as though there is little more to be achieved, unless there is a line fault which I very much doubt and the figures are broadly in-line with the distance from the cabinet to you house.

As you have seen, different modem types can connect at slightly different speeds - due to several factors in their design and even with two identical ones there can be differences due to tolerances.

Keep track using DSLStats with occasional screen shots or graphs just in case it does worsen.

Ensure that your house wiring is up to scratch. Install the modem as close as possible to the master socket, and if possible ensure the master is as close as possible to the point of entry. Keep electrical and electronic devices and power supplies away from the modem and line. You can run a Cat5e cable from the modem to your router giving you flexibility of placement for that. Run a single phone extension (if required) from the filtered side of the master without using the ring wire.

Thanks for your support - I have all your recommendations in place - the modem is about 1m away from the master socker which is at the place of entry and has an Openreach filter faceplate. the only phone is connected directly to the master socket faceplate. It's not a serious problem having the relatively slow upload but I thought that it was worth investigating.

You now, I hope, have a better understanding of what is going on.