learning VM image - 502 bad gateway error when launching PE Console

I'm just starting out with puppet, so tried the puppet learning VM image. I can't get the PE Console to open (task 4, power_of_puppet quest), instead I'm getting a 502 bad gateway, nginx/1.8.1 message. Has anyone seen this, or can provide some guidance on trouble shooting it? I'm using the CentOS7 image, puppet version 4.4.2. There appear to be two nginx instances running, from /usr/sbin/nginx, and also /opt/puppetlabs/server/bin/nginx - but I'm not sure if this is normal.. Thanks Phil