See the following troubleshooting resources for AWS.

Learning AWS can be a very long and daunting experience. There are dozens of primary services, each with hundreds of features to learn. However, very few things can be more frustrating than having connectivity issue when trying to access a provisioned AWS resource, like an EC2 instance.  After all, you just spent hours learning about AMIs, instance types, IP addresses, user-data, storage volumes, security groups, and key pairs.  Now you just want to actually access the damn instance and have some fun with it. But as you try to access the instance, whether by SSH or HTTP, you get one of these dreaded errors: “access denied,” or “operation timed out,” or some other variation.  Regardless of the error - you can’t log-in.AAAAARRRGGGGGG!Ok, so you vent a little bit – perhaps even yell at your computer.  Regardless of your frustration, you still need to figure out what is wrong.  With that in mind, I present some of the common (perhaps even simple) issues that cause many connectivity issues.