A SysOps administrator launches an Amazon EC2 instance in a private subnet of a VPC.

To resolve the issue of the EC2 instance in a private subnet not being able to connect to external websites via HTTPS (port 443), it is necessary to adjust the security group settings:

Outbound Security Group Rules: Verify that the security group associated with the EC2 instance allows outbound traffic on port 443 to any destination (0.0.0.0/0). This rule is crucial because it enables the instance to initiate HTTPS connections to external websites.

Network ACLs: While the primary concern here is the security group, ensure also that the Network Access Control List (ACL) associated with the subnet permits outbound HTTPS traffic. However, the ACLs by default allow all outbound traffic unless specifically restricted.

Internet Connectivity: Since the instance is in a private subnet, ensure that it has a route to the internet through a NAT Gateway or NAT Instance located in a public subnet. Without this, the instance won't be able to reach external networks even if the security groups and ACLs are correctly configured.

By ensuring that the security group permits outbound HTTPS traffic, you address the most common configuration oversight that would prevent such connectivity.