Unable to exchange UDP packets with node.js AWS server

Ideally, I would like to use my AWS instance to exchange UDP packets with various client applications.

When I run the server-side code locally, everything works as expected. However, when the code is run from AWS, no packets are detected. The logs tell me that, at least, the server-side send() is being invoked, but nothing else can be discerned. Also, I've enabled outbound/inbound UDP traffic.

Advice?