Hi!
Sorry for the late answer, something was very wrong with the support system.
Is the site url same on the VPN as it’s on the local server? I’m not sure if this is a client side or a server side issue, it can be both. But if the urls are different on local and VPN, then the ajax request fails because of the same origin policy. (the url of the wordpress installation is set to http://xxx.xxx and if you try to access it from the same virtual host address, for example http://yyy.yyy then the site may work, but the ajax requests fail because the site url tells a different address)