当我向URL添加端口号时，Google Maps API停止工作

I've been successfully using Google Maps API 3 for an internal web app using XAMPP server for a while, using the free access key provided to me by Google. I now want to expose this app to the internet, but I don't want to open port 80, so I set Apache to listen to another port (let's say 2880) and set up port forwarding. I am now able to access the web app at this port over the internet, but after Google Maps briefly loads the image it disappears, with a message to check the Javascript console. When I do, I see error messages such as 'MissingKeyMapError' and 'NoApiKeys'.I've been successfully using Google Maps API 3