Our SharePoint is using Azure AD as an Authentication provider. It was implemented based on this article - https://docs.microsoft.com/en-us/azure/active-directory/saas-apps/sharepoint-on-premises-tutorial
We have published our SharePoint via Application Proxy -> config was done based on this article https://docs.microsoft.com/en-us/azure/active-directory/app-proxy/application-proxy-integrate-with-sharepoint-server-saml
Login is working fine and SharePoint is available as expected.
Trouble:
If we try to open an excel file from the SharePoint site, we get the following error message(sign-in method insecure):
If I click on OK -> nothing happens
I i clock on Open Trust Center -> Following is displayed
There is now way to add a host or URL as a trusted location list.
This is happening on a brand new windows 10 and office 365 installation.
We would like to publish this webapplication to external users like customers or partners. So the client machines are not under our controll.
One workaround is to set a registry key, but it does not seems to be a real life solution: https://admx.help/?Category=Office2016&Policy=office16.Office.Microsoft.Policies.Windows::L_AuthenticationFBABehavior
This article explains the root casue, but we use AAD as an auth provider and we do not enabled Form Based Auth on our WebApplication: https://windowsmanagementexperts.com/did-you-know-there-is-an-updated-feature-restricting-form-based-authentication-in-office-apps
Any help is apriciated.