A couple of things to check
- Security group (you did that already, looks good)
- Subnet is public ? i.e. it has a Routing Table that includes a Rule that says 0.0.0.0/0 DST Internet Gateway
- Internet Gateway is attached to your VPC
On a side note, I would strongly discourage to make your database publicly available on the internet. In an ideal world, your database must have only a private IP address and must be available only from your app servers. Should you really need to be able to access your database from the Internet, your Security Group should be restricted to a /32 IP address
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…