1. 首先确保IAM执行角色已经被授予了必要的权限，包括:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ec2:CreateNetworkInterface",
                "ec2:AttachNetworkInterface",
                "ec2:DeleteNetworkInterface",
                "ec2:DescribeNetworkInterfaces"
            ],
            "Resource": "*"
        }
    ]
}

2. 然后，确保IAM执行角色是与目标EC2实例以及其VPC所属的子网关联的。在创建EC2实例时，可以提供以下IAM角色的ARN作为启动角色:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Stmt1234567890",
            "Effect": "Allow",
            "Action": [
                "sts:AssumeRole"
            ],
            "Principal": {
                "Service": "ec2.amazonaws.com"
            }
        }
    ]
}

3. 最后，确保IAM执行角色与特定VPC的相关联的网络接口。可以使用以下命令将网络接口附加到EC2实例:

aws ec2 attach-network-interface --network-interface-id eni-01234567890abcdef --instance-id i-01234567890abcdef --device-index 1