Is there a way to debug ODBC connections in Excel beyond the basic error message?

Yes, you can use Extended Events in SQL Server (if applicable) to trace the connection attempts and identify specific errors occurring during the connection process. Alternatively, you can use a dedicated ODBC tracing tool to capture detailed logs of the ODBC communication, which can help pinpoint the source of the 08004 error. The ODBC Data Source Administrator can also provide more detailed information about the connection attempt.