query-timeout

I have developed many .NET / SQL Server applications but I'm suffering from SQL query timeouts that I can't get to the bottom of. I have lots of experience in this area of finding the offending queries and re-indexing / re-writing them. My web app is hosted on AWS using RDS for SQL Server and EC2 for the Web App. We have 100-200 unique users per day and the database is around 15GB with a couple of tables > 1GB. I see exceptions throughout the day with the message: 'Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding.' The