If your application cannot reach a managed database, check from the outside in.
- Endpoint and port. Use the exact connection endpoint and port shown on the database instance under Databases. A typo here is the most common cause.
- Firewall. The database sits on your network. The server or app connecting to it must be allowed to reach the database port. Open that port to the app's address in your security rules, and keep it closed to the public internet.
- User and password. Confirm the database user exists and the password is right, and that the user is allowed to connect from the app's host.
- Same network. The simplest, safest setup is to keep the app and the database on the same private network so traffic never leaves it.
If the instance itself is unhealthy rather than unreachable, check its status under Databases and, if needed, contact support with the instance name and region.