Can't stream a socket connection in VPC

in the AWS EC2 Ireland region there is only the option of using VPC. However, I can't figure out how to stream data through a socket connection with another server outside of AWS. The server I am trying to connect to has a firewall where they only allow connections from a specific IP addresses. I am using an Elastic IP for this, but it isn't working.

Specifically, I am trying to use NodeJS to stream data with something like this:

var net = require('net');
var socket = net.connect(options, function(){...});
socket.pipe(...)

I am able to do this the same way in the N. Virginia region using classic EC2 (i.e. not a VPC), but I can't figure out how to get this to work with VPC. Any help would be appreciated. Thanks!