I have setup an 2016 RDS farm and I am trying access RDSH servers from outside the internal network through an RD Gateway server. I currently have it configured where users are directed to a WAP server (on port 443) in the DMZ that does pass through to the RD Gateway server (on port 443) on the internal network (The RD Gateway server also has the RD Web Access role on it). When I test connecting to an internal server through RD Gateway from a Win10 client on the internal network I can successfully RDP to an internal server. When I try to RDP from a Win10 client outside of the internal network through the RD Gateway nothing happens. I performed a wireshark capture from the WAP server and found that the external client never even gets to the WAP server. The internal client initiates the RDP communication on port 3389 to the WAP server and from WAP to RD Gateway on port 443, when initiating internally port 3389 is not blocked to WAP which is why it seems to work. I have configured the RDP client to use a gateway server address both internall and externally but the client keeps trying to initiate communication on port 3389.
My question is how do I configure the RDP client on a Win10 computer to initiate an RDP connection on port 443?