When you get a 502 it usually means that your reverse proxy is unable to connect to your backend server. I’m not sure if you’ve obfuscated the URL in your post but 0.0.0.0 is not a valid IP (it just means ALL IPs). If you are attempting to connect on the same machine that is hosting use 127.0.0.1. if you are on the same network then use the local IP.
What is a “feg”?