How to Fix AWS VPC Subnet No Internet Gateway

In this tutorial, you'll learn about How to Fix AWS VPC Subnet No Internet Gateway. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

Instances in your subnet cannot reach the internet — there is no Internet Gateway attached or the route table does not point to it.

Step-by-Step Fix

1. Check if an Internet Gateway exists

aws ec2 describe-internet-gateways --filters Name=attachment.vpc-id,Values=vpc-12345678

If no results, create one:

aws ec2 create-internet-gateway

Expected output:

{
    "InternetGateway": {
        "InternetGatewayId": "igw-12345678"
    }
}

2. Attach the Internet Gateway to the VPC

aws ec2 attach-internet-gateway --internet-gateway-id igw-12345678 --vpc-id vpc-12345678

3. Check the route table

aws ec2 describe-route-tables --filters Name=vpc-id,Values=vpc-12345678

4. Add a default route to the Internet Gateway

aws ec2 create-route --route-table-id rtb-12345678 --destination-cidr-block 0.0.0.0/0 --gateway-id igw-12345678

5. Verify subnet association

aws ec2 describe-subnets --subnet-ids subnet-12345678 --query 'Subnets[0].RouteTable'

6. Test internet connectivity

aws s3 ls

Common Mistakes

Prevention

• Use a default VPC for development (it comes preconfigured).
• Add Internet Gateway during VPC creation.
• Use NAT Gateway for private subnets.
• Document VPC architecture with route table mappings.

Common Mistakes with vpc subnet

1. Forgetting deriving (Show, Eq) on custom data types needed for debugging
2. Placing the wildcard pattern first in case expressions, making all subsequent patterns unreachable
3. Using head and tail instead of pattern matching, causing runtime errors on empty lists

These mistakes appear frequently in real-world AWS code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ