A centralized logging service running on EC2 receives logs from hundreds of AWS accounts using AWS PrivateLink. Each client account has an interface VPC endpoint for the logging service. The logging service runs on EC2 instances behind a Network Load Balancer (NLB) spread across subnets. Clients cannot send logs through the VPC endpoint. Which combination of steps should a solutions architect take to fix this? (Choose two.)

The issue of clients being unable to send logs through the VPC endpoint suggests a network connectivity problem. NLBs are transparent to security groups, meaning the security group on the EC2 instances must allow traffic from the NLB's subnets. Therefore, checking the security group for the logging service EC2 instances to ensure it allows inbound traffic from the NLB subnets is crucial. Additionally, NACLs are stateless and apply to all traffic entering and exiting a subnet. If NACLs are too restrictive, they can block traffic between the NLB and the EC2 instances. Verifying that NACLs attached to the logging service subnets allow traffic to and from the NLB subnets, and vice-versa, ensures proper data flow. The other options are incorrect because security groups for the NLB itself are not directly configurable in the same way as for EC2 instances, and allowing inbound traffic directly from clients to the EC2 instances bypasses the NLB.