Connecting CRM 2015 for Outlook to CRM 2015 On-Premise IFD : Authentication failed

Hi,

I am trying to connect the CRM2015 for Outlook plugin to a CRM2015 On-Premise IFD.

Everything works fine in the browser. I can access the organization from both the external and the internal url.

When I run the Configuraton Wizard it recognizes the organization, but when I enter the password I get this error message:

[Window Title]
Microsoft Dynamics CRM

[Content]
Mit dem Microsoft Dynamics CRM-Server kann keine Verbindung hergestellt werden, da Ihre Anmeldeinformationen nicht authentifiziert werden können. Überprüfen Sie die Verbindung, oder wenden Sie sich an den Systemadministrator.

[Expanded Information]
Authentication failed
   bei System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
   bei System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
   bei System.Windows.Forms.Control.Invoke(Delegate method)
   bei Microsoft.Crm.Outlook.ClientAuth.ClientAuthProvider`1.RetrieveUserCredentialsAndSignIn(Control parentWindow, Boolean retryOnError, IClientOrganizationContext context)
   bei Microsoft.Crm.Outlook.ClientAuth.ClientAuthProvider`1.SignIn(AuthUIMode uiMode, IClientOrganizationContext context, Control parentWindow, Boolean retryOnError)
   bei Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo`1.DeploymentInfo`1.LoadOrganizationsInternal(AuthUIMode uiMode, Control parentWindow)
   bei Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo`1.DeploymentInfo`1.LoadOrganizations(AuthUIMode uiMode, Control parentWindow, IClientAuthProvider`1 authenticatedProvider)
   bei Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo`1.InternalLoadOrganizations(DataCollection`1 orgs, AuthUIMode uiMode, Control parentWindow)

[^] Details  [OK]

[Footer]

And this is the relevant part of the configuration wizard log file:

10:46:10|   Info| Current UTC date/time from mydomain.LOCAL: 07/03/2015 08:46:10
10:46:10|   Info| NetApiStatus for NetApiBufferFree: 0
10:46:10|   Info| Client UTC Date/Time: 07/03/2015 08:46:10
10:46:10|   Info| Difference (in minutes) between client time and actual time: 0.000266705
10:46:10|Verbose| Method exit: Microsoft.Crm.Application.Outlook.ConfigDiagnostics.LocalTimeDiagnostic.ExecuteInternal
10:46:10|Verbose| Method exit: Microsoft.Crm.Application.Outlook.ConfigDiagnostics.DiagnosticEngine.Run(Environment)
10:46:10|Verbose| Method exit: Microsoft.Crm.Application.Outlook.Config.ServerForm.RunEnvironmentDiagnostics
10:46:10|   Info| Attempting IFD org service connection.
10:46:21|   Info| Error connecting to URL: {0} Exception: {1}| https://crm2015.mydomain.com:444/XRMServices/2011/Organization.svc, Microsoft.Crm.CrmException: Authentication failed
   bei System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
   bei System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
   bei System.Windows.Forms.Control.Invoke(Delegate method)
   bei Microsoft.Crm.Outlook.ClientAuth.ClientAuthProvider`1.RetrieveUserCredentialsAndSignIn(Control parentWindow, Boolean retryOnError, IClientOrganizationContext context)
   bei Microsoft.Crm.Outlook.ClientAuth.ClientAuthProvider`1.SignIn(AuthUIMode uiMode, IClientOrganizationContext context, Control parentWindow, Boolean retryOnError)
   bei Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo`1.DeploymentInfo`1.LoadOrganizationsInternal(AuthUIMode uiMode, Control parentWindow)
   bei Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo`1.DeploymentInfo`1.LoadOrganizations(AuthUIMode uiMode, Control parentWindow, IClientAuthProvider`1 authenticatedProvider)
   bei Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo`1.InternalLoadOrganizations(DataCollection`1 orgs, AuthUIMode uiMode, Control parentWindow)

The CRM server is a new deployment. Everything else seems ok.

The url from the log file (https://crm2015.mydomain.com:444/XRMServices/2011/Organization.svc) works, when I copy it into the browser.

Earlier another url was logged which couldn't be accessed from the browser, but after I followed these instructions:

https://www.interactivewebs.com/blog/index.php/crm-2013/adfsservicestrustmex-returns-503-on-crm-2013-windows-2012-ifd-mex-endpoint-fix/

the previous url could be accessed and the log started showing the Organization.svc-url.

Right now, I am out of ideas. Any help or suggestions would be appreciated.