>One important aspect of Setting up RDP is to change the default port. You may already have done that, but it's always good to remember. One of our clients learned this the hard way. See https://blog.emsisoft.com/en/28622/rdp-brute-force-attack/ under "Changing the RDP Port".

Changing the port is not the right way to protect RDS/RDP. You sometimes see that done if better methods have not been implemented. Better ways are setting up VPN access (not discussed in your link above) and using RD Gateway (which is briefly mentioned).

With either of those in place, changing the RDP port is unnecessary, and arguably counterproductive since it forces remote users to append the port number to connection settings etc and thereby becomes a support headache.