“localhost” normally points to the webserver on the machine the request is made from.
You installed wordpress on your server to run under “localhost”. So if you open a browser whilst on the server and go to “localhost” it will look for the site on the server and find it.
However, if you open a browser on your “dev machine” and go to “localhost” it will look for the site on your dev machine and it won’t find it there as you installed it on the server.
Now, if you’re connecting to the site using your server domain name (eg http://example.com), then whilst that request will work, the links to the images and other posts will not work because WordPress creates those links as “http://localhost/path/to/image/picture.jpg” which your browser will look for on your local machine and not find there.
The best solution: Logon to the site from a browser on your server and change the URLs in the dashboard to your server’s domain name and always use that domain name to connect to the site.