OK. I got routerstats working. Ironically, it was easier to get the full version working than the "plug and play" lite version. And the traces aren't very interesting so far. Completely flat-lining. No variation. Not one pixel.
And here is a little more background on the line to our house. I'll try to say more than less, in case something apparently trivial is actually significant.
Along our road near our house there are a couple of telephone poles, with a star configuration of wires feeding out to the various houses near each pole. This is, I guess, pretty normal.
My house and that of our neighbour (the one I mentioned as having a better broadband speed than me in the original post!) are served from the same pole. Their house is admittedly closer to the pole than ours, but I doubt that would make a huge difference: we're talking at most 50 yards difference here.
Our line from the pole is supported on the corner of their house before arching across to ours. From our eaves, a cable runs down our wall to a rather ancient looking weather-protected junction box, entering from below.
Another cable runs down away from the box junction box from its below, and straight down into the ground. No evidence of any other cables emerging from the earth nearby.
Opening up the junction box is easy: there is a large thumb screw on the front; no screwdriver required.
Inside this box are eight junction contacts, but in fact no wires are connected to these. Instead, the two cables entering the box are merely connected one to the other, with the connections using the weather protection of the junction box.
The connections (or not) of the wires are as follows:
Upper Orange to Lower Green
Upper White to Lower Blue
Upper Green and Blue not connected to anything
Lower Orange and White not connected to anything
I am not sure exactly how the wire from outside reaches the phone point to which my router is connected (it's not on an external wall). Our digital phone is connected to a different phone point in the next room, and again it's not apparent how the line gets there -- again it is not on an external wall. The cable outside disappears into the ground, and magically pops up somewhere in the house.
I've tried turning off and disconnecting the phone completely. This didn't have any effect on the routerstats trace. Not sure that it would.
Nothing else in our house is connected to the phone line. There are a couple more phone points around the house, not all of which work. Again, it's not apparent how the wiring gets there. This is a 1960s house extended several times over the years.
So, that's it for now. The only thing which strikes me as a bit odd are the connections described above: is it really normal to connect orange to green and white to blue?? The phones all work OK, so it can't be too drastically wrong, but it still seems odd.
Thanks,
Mike