An ASP.NET Core API times out while SQL Server CPU is low. What would you investigate?

Low SQL Server CPU does not prove the database is healthy. The request may be waiting rather than consuming CPU.

Check blocking and lock waits, storage latency, transaction-log flush latency, memory-grant waits, connection-pool exhaustion, network latency, external API calls, thread-pool pressure, command timeout settings, and long transactions.

Correlate the ASP.NET Core request trace with SQL Server sessions, Query Store, Extended Events, and application telemetry. Determine where elapsed time is actually being spent before changing timeout values.

Increasing CommandTimeout can hide the symptom without fixing the underlying bottleneck.