The support for configuring the same port number for public and private listeners on your Application Gateway is now generally available.
The provision enables you to easily use a single Application Gateway deployment to serve both internet-facing and internal clients. With this, you don't need to use non-standard ports on listeners or customize the backend application. This feature is now generally available in all public regions, Azure China cloud regions, and Azure Government cloud regions.
An additional configuration may be needed for Inbound rules if you use Network Security Groups with your application gateway.
Learn more.