Did you ask Q?
There are a few common reasons why you may be unable to SSH into your server instance:
Security group rules are not configured to allow inbound SSH traffic on port 22. Check that your security group allows SSH from your IP address or network.
The key pair you are using does not match the private key file stored locally. Make sure the private key file matches the key pair assigned to the instance at launch.
Firewall rules on the instance itself may be blocking SSH connections. Check for any firewall software like ufw that could be blocking port 22.
Network ACL rules are too restrictive and are blocking port 22 traffic. Confirm your subnet network ACL allows inbound SSH traffic.
The SSH service may not be running on the instance. Connect to the instance via its server Instance Connect feature to check if the SSH daemon is active.
To troubleshoot further, try connecting with verbose logging ssh -v to see where the connection is failing. You can also check firewall and security group logs on the instance for any rejected connection attempts. The AWS documentation on troubleshooting SSH connectivity provides additional tips on resolving common issues.
FYI: The more v's the more verbose the output...ssh -vvv