Sandbox container CT 120 is up and this hostname resolves and serves TLS correctly. No application is deployed yet.
This page exists so that an empty sandbox is distinguishable from a
broken one. A 502 Bad Gateway here would mean the proxy cannot reach
the container; this page means it can, and the container is simply waiting for an
app in /opt/affiliate.
Replace this placeholder by deploying a stack that listens on port 80 inside the container.