Getting higher than normal latency on EC2

If you're experiencing higher than normal latency on your EC2 instance, there are several potential causes and troubleshooting steps you can take:

1. Measure and identify the issue: Use the curl command to measure response times and identify where the latency is occurring:

curl -kso /dev/null -w "\n===============
| DNS lookup: %{time_namelookup}
| Connect: %{time_connect}
| App connect: %{time_appconnect}
| Pre-transfer: %{time_pretransfer}
| Start transfer: %{time_starttransfer}
| Total: %{time_total}
| HTTP Code: %{http_code}\n===============\n" https://destination-address

2. Run traceroute: Perform a traceroute to the IP address (111.223.59.139) to identify where in the network path the latency is being introduced.

3. Check network configuration: Verify your VPC settings, security groups, and network ACLs to ensure they're not causing delays.

4. Instance type and networking: Ensure you're using an instance type that supports enhanced networking and that your network settings are optimized for low latency.

5. ENA driver settings: If your instance uses the Elastic Network Adapter (ENA), review and adjust the driver settings using 'ethtool' to minimize latency.

6. MTU settings: Check the Maximum Transmission Unit (MTU) settings, which can vary depending on your specific location.

7. Monitor CloudWatch metrics: Review NetworkIn, NetworkOut, and NetworkPacketsIn/Out metrics for unusual patterns.

8. Test from different locations: If possible, test connectivity from different AWS regions to determine if the issue is location-specific.

If the issue persists after these steps, consider contacting AWS Support, especially if you're on a paid support plan. They can provide more detailed analysis of your specific situation and network conditions.
Sources
Chicago Local Zone Latency | AWS re:Post
Troubleshoot latency on calls or requests to Amazon ECS tasks | AWS re:Post
Higher network latency since 1st of May | AWS re:Post