Possible reasons for timeout when trying to access EC2 instance

Question

I cannot SSH into my instance - Operation timed out. What could be the reasons why, and what can I do to resolve it? Rebooting normally takes a long time to take effect, an

Answer 1

This answer is for the silly folks (like me). Your EC2's public DNS might (will) change when it's restarted. If you don't realize this and attempt to SSH into your old public DNS, the connection will stall and time out. This may lead you to assume something is wrong with your EC2 or security group or... Nope, just SSH into the new DNS. And update your ~/.ssh/config file if you have to!