usually laws of hydraulics apply

but why measure downstream of a buffer ?

No idea. I was just trying to visualise what the information in the speedtest.net link actually represented.

No, it's not a contradiction so long as we ignore the milliseconds between the two updates. In effect it is a real-time update, so the value is not historical in the system design sense.

I accept that if the update fails, it could be argued that it is an historical figure but I feel the argument would be spurious.

In particular, we don't even know, at least I don't, which updates first. They may both update from feeds from the same source, not one from the other.

This argument in itself is fairly pointless and silly, distracting from the thread discussion. As I said before, it seems the two can get out of step, thus potentially causing apparently impossible speed test results.

if it can get out of step it's not a real time value, so comparing a historical record of a limit against the current value of a speedtest doesn't tell us anything of significance.

The title should be be "Speed above alleged IP profile" or "Speed above historical record of IP profile"

If the speed test doesn't report the value prevailing in the BRAS at the time the test was executed, it's historical.

Sorry Officer, I was within the speed limit that I recall was in operation last Thursday