From https://www.spark.co.nz/help/internet/troubleshoot/broadband-speed/ Click the link a get this:
its not an official support channel though people do it out of the kindness
Known issue. The speedtest servers are fine - the specific embedded URL in that page isn't working. That URL was mapped to the Spark wellington Ookla Speedtest server so if you want to compare old results - use that one.
Cheers - N
Please note all comments are the product of my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.