EC2 Server actively refusing Perforce Connections

This issue where your EC2 instance is suddenly refusing Perforce connections after working fine for years is likely related to one of several possible causes:

1. The Perforce service on your EC2 instance may have stopped running. When a service isn't running, connection attempts are actively refused by the operating system.

2. There could have been a system update or reboot that prevented the Perforce service from starting automatically.

3. Security group settings might have changed, though this typically results in timeouts rather than connection refusals.

To troubleshoot this issue:

1. First, try to connect to your EC2 instance using SSH or EC2 Instance Connect through the AWS Console. This will help determine if the instance itself is accessible.

2. Once connected, check if the Perforce service is running using a command appropriate for your operating system (like systemctl status perforce or service perforce status).

3. If the service isn't running, try starting it manually.

4. Check the Perforce server logs for any error messages that might explain why the service stopped or failed to start.

5. Verify that there's enough disk space and memory available on your instance, as resource constraints can cause services to fail.

6. Ensure that port 1666 (the default Perforce port) is still open in your security group's inbound rules.

If you're unable to connect to the instance at all, you might need to check the instance's system logs through the EC2 console to look for any boot or system-level issues.

The "actively refused" error specifically indicates that your EC2 instance is reachable, but the Perforce service isn't accepting connections, which points to an issue with the service itself rather than network connectivity.
Sources
Suddenly I can't connect to my ec2 server | AWS re:Post
EC2: Cannot connect anymore via Instance Connect or SSH command line | AWS re:Post