如果您使用AWS CloudFront和ELB来处理请求，并且发现请求无法到达后端，请按照以下步骤进行排查。

1. 确认您的域名是否正确解析到了CloudFront和ELB。可以使用dig命令进行验证。

2. 确认您的CloudFront设置是否正确。您需要将CloudFront的Origin设置为ELB，并在Behaviors设置中指定要转发的路径。请参考下面的代码示例：

"Origins": {
  "Quantity": 1,
  "Items": [
    {
      "Id": "myELB",
      "DomainName": "my-elb-domain-name.amazonaws.com",
      "CustomOriginConfig": {
        "HTTPPort": 80,
        "HTTPSPort": 443,
        "OriginProtocolPolicy": "http-only"
      }
    }
  ]
},
"DefaultCacheBehavior": {
  "TargetOriginId": "myELB",
  "ForwardedValues": {
    "QueryString": true,
    "Cookies": {
      "Forward": "all"
    }
  },
  "ViewerProtocolPolicy": "redirect-to-https"
}

3. 确认您的ELB设置是否正确。您需要为ELB创建正常运行和故障转移引用程序。请参考下面的代码示例：

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Resources": {
    "MyELB": {
      "Type": "AWS::ElasticLoadBalancingV2::LoadBalancer",
      "Properties": {
        "Name": "my-elb",
        "Scheme": "internet-facing",
        "Type": "application",
        "Subnets": ["subnet-12345", "subnet-67890"],
        "SecurityGroups": ["sg-12345"],
        "LoadBalancerAttributes": [
          {
            "Key": "access_logs.s3.enabled",
            "Value": "false"
          }
        ],
        "Tags": [
          {
            "Key": "Team",
            "Value": "MyTeam"
          }
        ]
      }
    },
    "MyTargetGroup": {
      "Type": "AWS::ElasticLoadBalancingV2::TargetGroup",
      "Properties": {
        "Name": "my-target-group",
        "VpcId": "vpc-12345",
        "Protocol": "HTTP",
        "Port": 80,
        "Matcher": {
          "HttpCode": "200-399"
        }
      }
    },
    "MyListener": {
      "Type": "