Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'. Reason: Token-based server access validation failed
This is known as the "double hop" issue between SQL Server and IIS. It looks like you may not have trusted the IIS server for delegation.

Here's a good checklist of things to do when setting up SQL Server with IIS using Kerberos.

Here's a great primer on the condition. The anonymous login is a give-away of the problem.