One likely problem is that the IP addresses you're being shown to use for the connections are not right. MultiChain nodes apply a heuristic to discover their own IP addresses, which are displayed to you, but this heuristic can be wrong in unusual setups. Please try connecting using the appropriate external IP address.
Another likely problem is that the (software) firewall running on the cloud EC2 instance is blocking incoming connections on the appropriate port. It's beyond our scope here to give specific instructions for resolving that, but iptables is a good place to start.
