What’s failing is DNS resolution. When you are doing curl from the commandline the first place that your nameserver will check for definitions is your /etc/hosts file. If there you have a definition for a domain or name to point to an IP then it will use that to make the request.

When you are going from your browser there is similar behavior depending on whether you are using Mac or Windows. So most likely there is a misconfiguration between your /etc/hosts setting between your server and your local machine which is why when you goto the browser you get the error.

Now if you have a full domain in there, instead of mysitename as a place holder, you would need to check DNS resolution of that domain from both environments to see what the issue is.