You are managing a Shared VPC in a host project. Multiple departments within your organization have infrastructure deployed in various service projects connected to the Shared VPC, using IAM permissions to control cloud resources in those projects. VPC Network Peering is configured between the Shared VPC and a common services VPC outside of any service project. Some users report connectivity failures between specific instances across different Shared VPC service projects, as well as between certain instances and the internet. How should you verify the network configuration to determine if a misconfiguration is causing these issues?