Connection reset on Docker Playground when connecting to base app.

[infinityredux]

Using the docker playground to run the tutorial and I've run into an issue getting the app to work correctly in the second stage "Our Application".

Steps to reproduce (essentially just follow the instructions):

1. Launch a Docker Playground instance.
2. Run the command docker run -dp 80:80 docker/getting-started:pwd (as per https://www.docker.com/101-tutorial )
3. Connect to the tutorial by opening port 80 (click the link there)
4. Download the app.zip file from the tutorial.
5. Upload the zip file to the playground instance and unzip.
6. Create the Dockerfile following the instructions.
7. Build the docker image.
8. Start the container running.
9. Attempt to connect to the app.

Expected result: Connecting to the node todo app.
Actual result: Connection reset error.

I assume the difference between running the tutorial locally and in the playground is the reason for the differences in the image files (the :pwd at the end.)

I've tried this running on a separate instance from the main tutorial, even changing the port to 80 in case of some weird playground firewall (because that port works for the tutorial itself.) Even attempting to connect locally to the port (within the playground) results in errors (e,g, from Curl: curl: (56) Recv failure: Connection reset by peer)