Thanks candlerb.
TAP-Windows Adapter V9 Windows shown as being used.
The Surfbook can be connected to a router via an ethernet cable either by using a cable with a USB plug or to the ethernet port in its docking station.
I am getting 300 MBPS over wireless on the Surfbook close to the router.
There is a 400 MBPS 2.4 Ghz limit on this router. You can go higher at 5 Ghz.

Tx techguy.

Zen came on to the router via the internet and confirmed the 1 GBPS as you suggested.

I have left a feedback for Msft.

Windows updates all installed.

Are you running the original Surface Dock or the second generation?

Had a search and there have been earlier reports of network speed issues on the first generation dock in this article

You may want to check that you are running the most up to date firmware on the dock and W10 drivers

See for example:

1. Surface Dock 1 firmware update instructions from Microsoft and link to files here

2. The cumulative and current firmware and drivers for the Surface Dock 2 here

Looks like both were last updated on Friday.

Tx Canlerb.

Using 2bn generation. As you say, first had problems. It was underpowered. I will update the firmware. Tx for the tip.

Should have made clear, I also used (instead) the cable adapter, the cable with an Ethernet plug at one end and a USB plug at the other.

Ad Ubuntu got 887 through the dock, I ruled it out.

I am afraid it is Zen’s problem for not mentioning the problem which they have admitted they knew about affecting Windows 10 when selling a service that they said would provide a 900 download speed into a market heavily if not largely populated by Windows 10.

How do you fit a network card to laptop?

Zen (or for that matter any other ISP) have no control, influence, contractual or otherwise responsibility (other than perhaps giving you some hints and tips, which again are not binding on them) over what you connect to their service.

The harsh practical and legal reality is that your own home network and your devices are wholly and solely up to you.

The ISP responsibility starts and finishes at their network handover point - the rest is up to you. Whether you perceive the market to be heavily dominated by W10 is of no consequence really.

I am afraid it is a simple matter of contract law. ISPs like the rest of us have to leve with it.

You cannot make false representations

In reply to a post by JMaples:

I am afraid it is a simple matter of contract law.

Yes, and you demonstrated in your OP (by using Ubuntu) that Zen have fulfilled their side of the contract by providing a service that meets the advertised claims.

That your preferred choice of system is one that cannot cope with it is your problem, not Zen's.

In reply to a post by JMaples:

I am afraid it is a simple matter of contract law. ISPs like the rest of us have to leve with it.

You cannot make false representations

The ISP is responsible for getting the speed to the router that they provide.

You are responsible for your own equipment not being powerful enough.

The issue isn't with Windows. It is an issue with YOUR installation of Windows.
Windows is more than capable of delivering 900Mbps.

According to Zen it is a Windows10 power management problem so not particular to me. It was something Zen were aware of when selling me their product. They should have disclosed what they knew instead of keeping silent and taking the money.