Behavior 1:
Windows Login is used. If you run a search at the Microsoft Sharepoint within the result list appear following error message:
"Login failed for user NT AUTHORITY\IUSR"
Cause:
Anonymous user is used, somewhere on the way from Sharepoint to the SearchFederationServer.
Solution:
The websites and the website of the Webservices have Anonymous and Trusted Login enabled. Deactivate the anonymous authentification.
Behavior 2:
You want to create a new web instance but it will not appear in the context menu. And the option "Create New Webinstance" is greyed out at "Edit" .
Cause:
The modul "Connect to MFP" is not installed.
Solution:
You need to install the missing modul to that machine where the IIS and the "Web Modules" are installed.