Troubleshooting EC2 Instance Connectivity Issues Step-by-Step

So, your EC2 instance isn’t connecting. Annoying, right? Whether you’re troubleshooting SSH, RDP, or even web access, figuring out what went wrong can feel like untangling a ball of cables. Let’s take it step by step to get your instance back online.

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First Things First: Understand the Issue

What exactly isn’t working? Can’t SSH in? Website not loading? Identify the problem clearly before diving into fixes.

“Why do I always get connection timeouts?” a colleague once asked. The answer wasn’t magic; it was a misconfigured security group.

Let’s get started.

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Step 1: Check Your Instance’s Status

Head to the AWS Management Console. Under the EC2 dashboard, look at the instance’s State.

• Is it running?
• Does it have a public IP?
• Are there any warning flags?

AWS makes it easy to spot obvious issues. If your instance is stopped or terminated (it happens!), you’ll need to restart or recreate it.

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Step 2: Review Security Groups

Now we’re getting to the nitty-gritty. Security groups act as firewalls for your instance. Go to Security Groups in your EC2 settings and look for these rules:

• Inbound rules: Do they allow the protocol you’re using (SSH = port 22, RDP = port 3389)?
• IP range: Are you allowing traffic from your IP or just 0.0.0.0/0?

Pro Tip: If you’re unsure of your current IP address, just Google “What’s my IP?”

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Step 3: Test the Network

If the security group checks out, move to the network interface. Is it attached? Does the subnet allow internet traffic?

Run these quick tests from your local machine:

• Ping the public IP.
• Use a tool like telnet to check if the port is open.

Here’s a command to test SSH:

telnet [your-EC2-public-IP] 22  

If it times out, the issue might be with your network configuration.

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Step 4: Key Pair and Login Credentials

Ever try opening a lock with the wrong key? Same story here. Make sure you’re using the correct private key file for SSH. If you’ve lost it (oops), you’ll need to create a new key pair and update your instance’s settings.

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Step 5: Dive Into the Instance

Still stuck? Use the System Log feature in the EC2 dashboard. It provides details about startup issues, missing configurations, or errors preventing a connection.

For Linux instances, you can also use AWS Systems Manager Session Manager to get terminal access without relying on SSH.

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Step 6: Check Route Tables and Gateways

This one’s sneaky. If your instance is in a private subnet, it needs a NAT Gateway or Internet Gateway to access the internet. Navigate to your VPC settings and ensure the correct route table is attached.

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Real-Life Troubleshooting Example

Last week, I was helping a team access their EC2 instance. Everything looked fine—until we realised the private key didn’t match the public key. Once we updated it, the connection worked instantly. It’s usually the small things that trip you up.

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Additional Resources

Here are some helpful links if you want to dig deeper:

• AWS EC2 Troubleshooting Docs
• Guide to Key Pair Management

Looking for internal tips? Check out our guide on adding DNS servers using PowerShell or configuring an S3 bucket for file sharing.

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Final Thoughts

Troubleshooting connectivity is like solving a puzzle—frustrating but rewarding once you get it right. Did this guide help? Let me know if you have questions or tips to share. After all, tech is better when we figure it out together.