When connecting to SQL datasources (except for BigQuery) we will always connect from 54.68.61.53. Some providers and set ups likely require granting access on a per-IP basis. Use the following guides to learn how:
AWS RDS (Postgres, MySQL, SQL Server)
If your provider is not listed above follow your hosting providers instructions for allowing connections from 54.68.61.53. For MySQL, Postgres, and Redshift connections you may also connect through an SSH tunnel.