How do I investigate the cause of lengthy timeouts on an EC2 instance.

What is the CPU utilization and do you have the Cloudwatch agent installed for memory utilization? https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Install-CloudWatch-Agent.html https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/metrics-collected-by-CloudWatch-agent.html

You could also set an alarm on high memory utilization and if it peaks (or a notification from the WP system/SNS) to have Lambda restart the instance for you. Depending on architecture you can also use a AutoScaling Groups with 1 instance minimum + health check for this same purpose.

Following the start of the last timeout event the %CPU utilisation dropped from 11% to 2% in a period of 2minutes. It stayed at around 2% until the instance was stopped/started. Any further assistance would be much appreciated.