Set up Reversed Proxy in Internet Information Service to reach Webbrowser on a PLC from WinCC Unified

Question

i need to set up a reversed proxy to reach a Webbrowser of a PLC (Win CC Unified). The problem is that im not able to change Server header rules for "X-Frame". I found a lot ot tutorials but i was not able to set up the reverse proxy correctly.

Thats the link to the webbrowser: https://192.168.73.2:343/Portal/Portal.mwsl?intro_enter_button=WEITER&PriNav=Start&coming_from_intro=true&no_intro=on

1. Add new Site to IIS
2. Typ https and choose SSL Certificate
3. Change Port to 4434 because 443 already taken
4. URL Rewrite -> add Rule -> Reversed Proxy
5. Add link
6. Rewrite the domain names of the links in HTTP repones
7. add name of the pc (in my case M1234) at To:

Now i think it should be possible to reach Webserver with the folloing link: https://m1234:4434

But its not working. Can someone give me a hint? I get following error msg:

HTTP-Fehler 502.3 - Bad Gateway The server name or address could not be resolved Error code: 0x80072ee7

Im a totaly beginner so please give me answers on a beginner level.

If you know an easier way to work around missing X-Frame rules, i would really like to hear about it.

Thanks