match the connection setup to the auth mode or you will chase the wrong failure. SQL auth: DB_URL like jdbc:sqlserver://your-server.database.windows.net:1433;database=your-db;encrypt=true, DB_USER as plain username, no authentication key in the URL. Entra password auth: same URL but add authentication=ActiveDirectoryPassword and set DB_USER to the full [email redacted]. If the tenant requires MFA, stop trying passwords, they cannot work: switch to a service principal or managed identity. Quick sanity checks before deeper debugging: curl https://api.ipify.org to get your IP and add it as a firewall rule with az sql server firewall-rule create, then nc -zv your-server.database.windows.net 1433 to confirm TCP reachability. If the pool reports zero total connections, the problem is auth or network, not your SQL.