Lose connection when enabling HTTPS

When enabling HTTPS access per:
https://nodered.org/docs/user-guide/runtime/securing-node-red
I can no longer connect to Node-RED and receive a "This page isn't working" ERR_EMPTY_RESPONSE error message.
I've checked for spelling errors, path to certificates, and am at a loss as to what to look into next.
I know the certificates themselves are fine as the HTTPS connection to PostgeSQL works fine.

Anyone have an idea of what I should be checking out as a possible problem?