In Sharepoint 2010, we have a farm with three WFEs.
We use a BDC with a connection string with integrated security to a SQL Server 2008 R2 DB and then a list linked to this BDC to show the contents of a table (simple select statement). We expect the connection to use the application pool account because we use forms authentication for the users and cannot impersonate them. It has read permissions into the DB and table. Kerberos is not implemented in the network.
In two of the WFEs the BDC works correctly and the list shows the contents of the table, in the other WFE it doesn't and fails with "Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON" message.
We tested with a simple ASP.Net site with a page that shows a gridview linked to this same table with the same connection string in the web.config as the BDC, we created a web site in the same IIS and the same application pool, and it worked, showing the contents of the table.
This third WFE was added later to the farm, so far all the comparisons in filesystem conf files, IIS config, etc. yield the same configuration. ¿Are we missing something?