> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dexdata.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting connections

> Common connection errors and a pre-connection checklist.

## Common connection errors

* **Connection timed out** — Firewall blocking access. Fix: whitelist Dex's IP in your firewall or security group.
* **Authentication failed** — Wrong username/password. Fix: double-check credentials and reset the password if needed.
* **Database does not exist** — Typo in database name. Fix: verify the exact database name (case-sensitive for some DBs).
* **SSL required** — Server requires SSL. Fix: enable SSL mode in the connection settings.
* **Invalid API key** — Wrong or expired key. Fix: generate a new API key from the provider dashboard.
* **Permission denied** — User lacks privileges. Fix: grant SELECT or read permissions to the user.

## Connection checklist

Before connecting, verify the following:

* Your database/service is accessible from the internet (or Dex's IP is whitelisted).

<Note>
  If your source is behind a firewall or private network, add this Dex outbound IP address to your allowlist before testing the connection: **44.216.91.118**.
</Note>

* The user or service account has read access to the target database/schema.
* Credentials are correct and not expired.
* The correct port is open (PostgreSQL: 5432, MySQL: 3306, Redshift: 5439).
* SSL certificates are valid if using SSL.