Windows Host & AD authentication Providers issue

Hi There

I have setup an Authentication Provider for Windows 2008 R2 AD controllers as follows:

Name:Domain

Type:Active Directory

Domains: mydomain.com

Server URLs: ldap://IP

Manager DN: CN=account,OU=users,DC=domain,DC=com
Group Attribute: CN

Search Scope: Subtree

Search Base: DC=domain,DC=com

Search Filter: userPrincipalName=%u

which seems to work ok.

when I try to add a windows host I get

Failed to connect to host. Please ensure the connection details are correct. [Authentication Failed]

on the host WinRM is configured

C:\>winrm quickconfig

WinRM service is already running on this machine.

WinRM is already set up for remote management on this computer.

firewall is open for winrm (have also tried with firewall off)

can connect remotely with powershell with no issues.