Which of the following options provide a viable solution to remedy this situation?

Explanations:

Adding a route to the route table with an IPSec VPN connection as the target is not necessary or appropriate when a Direct Connect connection is established. Direct Connect should be used directly to route traffic without needing a VPN target, as it is a dedicated link.

Enabling route propagation to the virtual private gateway (VGW) allows the VPC to automatically learn routes from the on-premises network, facilitating proper routing of traffic between the VPC and the customer’s datacenter through Direct Connect.

Route propagation to the customer gateway (CGW) is not applicable as CGWs do not support route propagation. Instead, routes need to be manually configured on the customer side, so this option does not provide a solution to the connectivity issue.

Modifying the route table of all instances using the ‘route’ command would not resolve the issue. Route modifications should be done at the VPC route table level, not at the instance level, and would not affect overall connectivity through Direct Connect.

Modifying the Instances VPC subnet route table by adding a route back to the customer’s on-premises environment allows traffic from the VPC instances to reach the on-premises servers. This ensures that there is a valid route for the return traffic, enabling successful communication between the two networks.