Verify that the StoreFront resolves the base URL to itself by pinging base URL from the StoreFront command line. If it does not resolve to the base URL then make an entry in the host file on StoreFront so that the base URL resolves to itself.
You can also check to see if the page loads from the storefront server it’s self. If you copy the Receiver for Web URL, and change the domain to local host, it should load a storefront page. It will look similar to this http://127.0.0.1/Citrix/StoreWeb
If you still get 404 after testing reachability on the storefront server it’s self, it is recommended to bring in a Storefront engineer for further troubleshooting.