Laravel Forge Server Network Not Connected?

Context

I've set up two servers in AWS via Forge. One is a web server, the other a database server.

I've allowed each server to connect to the other via each server's Network tab. The default firewall rules open up ports HTTP (80) and HTTPS (443).

Problem

When testing the app in the browser, the static pages work great, but any pages requiring database access hang for a bit, then nginx throws a 504. (I can connect to the database server via Sequel Pro, so my credentials are accurate.)