OP is outside VDSL2 coverage and right on the outskirts of ADSL2+ coverage in Titahi Bay. There isn't any valid netmap data for the address so it's not possible to know exactly what speeds could/should be. It is entirely possible that to get to this location that the MPF routing is exceptionally poor, but I still wouldn't pick it as being anywhere near long enough to match up with the attenuation figure.