Windows Server 2016 Remote Access Server Event ID 4402 NPS Error

We are seeing the following on our remote access 2016 server:

Log Name:      Application
Source:        NPS
Date:          01/11/2018 16:00:47
Event ID:      4402
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      %computername%.domain.suffix
Description:
The description for Event ID 4402 from source NPS cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event:

DOMAIN

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="NPS" />
    <EventID Qualifiers="49152">4402</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2018-11-01T16:00:47.901902800Z" />
    <EventRecordID>2591</EventRecordID>
    <Channel>Application</Channel>
    <Computer>%computername%.domain.suffix</Computer>
    <Security />
  </System>
  <EventData>
    <Data>DOMAIN</Data>
  </EventData>
</Event>

We are using a signed certificate and are stuck trying to get this to work - how do we test the clients? They do not seem to have any connectivity even after syncing the GPOs

We are also struggling with the VPN settings for Windows 10 on SSTP

Do not use a signed certificate - just stick with the defaults offered by the system - it will configure the clients to trust the certificate by GPO anyway and allow the systems to connect without issue. Also if you are using a real URL domain - .co.uk or similar, make sure you use a different domain for the remote access server connection so that the system does not get confused, register a .info or something and use that as the external connection.