Thanks for all the suggestions guys.
I did boot my desktop to Ubuntu through USB doing the tests but there is no change.
The surface dock is connected to surface book with it's special connector(I think all surface got this connector since gen 4), it has 1 gigabit ethernet + 2 displayport + 4 usb3 so I guess it should have enough bandwidth to handle a gigabit network.
I just tried different server locations as suggested:
Dunedin 2degrees: 124mpbs down, 100mbps up
Wellington Spark: 136mbps down, 201mbps up
Wellington Vodafone: 230mbps down, 114mpbs up
Auckland Spark: 126mpbs down, 183mbps up
Auckland Vodafone: 130mbps down, 131mpbs up
Auckland MyRepublic: 336mpbs down, 138mbps up(wait...)
Auckland 2degrees: 934mbps down, 151mpbs up(huh??????)
Sydney Vodafone: 238mbps down, 81mpbs up
Sydney 2degrees: 814mbps down, 76mpbs up(what???)
From the results I guess the fibre is gigabit although it only can achieve that on 2 of the 2degrees servers? So the problem is Spark's speedtest server is overloaded then...
I can guarantee you that the Spark Speedtest servers are not overloaded. Given the numbers you have shown above are all over the place I still suspect weirdness in your network or PC setup.
Cheers - N