How to forward a port on a router for RDP Gateway?

Question

network hardware

There is a router with a real external IP address.
There is a local area network with the gateway of remote desktops.
I read the description of the gateway on technet:

RD Gateway passes RDP traffic on port 443 using an HTTP tunnel with SSL and TLS protocols. Because most organizations open port 443 to connect to the Internet, RD Gateway takes advantage of this network design to allow remote connections through multiple firewalls.

It is not clear how to set up forwarding on the router so that when connecting to the router, the client connects to the gateway.
If I just do Port-Mapping, router:443 > gateway:443, will this somehow affect network clients who also use the router to access the Internet? They also use port 443 for secure connections through NAT. And here it turns out stupidly any external request for 443 will just be sent to the gateway?

Answer 1

If I just do Port-Mapping, router:443 > gateway:443, will this somehow affect network clients who also use the router to access the Internet?

It will not affect in any way. They do not go to sites that are under the router, but to other sites that are behind it)
No, nat creates connections on random ports and obviously not on this one) I recommend that you read and better understand the topic.