 <p>Heroku dynos are all running on machines within Amazon EC2 us-east-1 data center. They do not have any restrictions/firewalls on outgoing connections.</p> <p>As long as you have the proper Security Group settings to allow the connections from your dynos to your own EC2 instance, you should be good.</p> <p>It sounds like you haven't correctly opened up access from within us-east-1 to your instance. Double check your security group.</p> <p>Information on how to edit the correct security group:</p> <ol> <li>Check what security group you are using for your instance. See value of Security Groups column in row of your instance. It's important - I changed rules for default group, but my instance was under quickstart-1 group when I had similar issue.</li> <li>Go to Security Groups tab, go to Inbound tab, select HTTP in Create a new rule combo-box, leave 0.0.0.0/0 in source field and click Add Rule, then Apply rule changes.</li> </ol>