No, it shouldn't be an issue if you're using an IP in the config.js since the proxy config does not filter for a specific hostname.
Sound to me, like the containers didn't start properly or a connection issue from the VM to the client (due to firewall settings maybe).
You can check if the containers are running properly by running
sudo docker ps.
In the list, all necessary containers should be listed as well as their startup time. If one or more of the four containers is not having the same startup time as the others, you can identify which container tries to restart/fails.
Also, as Norbert said, if there's already a service running on port 80 ( check
netstat -tunap ) you might want to either stop that service or configure your
docker-compose.yml file to use a different port.
In this case, change:
(don't forget to update your
config.js from port "80" to "8585", restarting the containers with
docker-compose up -d and using that port in the browser address bar "http://myserver:8585")