If you need to add a reverse proxy to your Internet Information Server (IIS) you can just add a rule to your site configuration file. In the following example we add a reverse proxy (url rewrite) for a GraphQL Server to our WinCC Unified WebRH. Afterwards restart the site with the IIS services manager.

IIS Configuration File: 
"C:\Program Files\Siemens\Automation\WinCCUnified\SimaticUA\web.config"
 
 <configuration>
   <system.webServer>
     <rewrite>
       <outboundRules>
         <rule name="Remove Server header">
           <match serverVariable="RESPONSE_Server" pattern=".+" />
           <action type="Rewrite" value="" />
         </rule>
       </outboundRules>
             <rules>
                 <rule name="Reverse Proxy to GraphQL" stopProcessing="true">
                   <match url="^graphql" />
                   <action type="Rewrite" url="http://localhost:4000/graphql" />
                 </rule>                      
                 <rule name="UMC SSO Static">
                     <match url="(.*)" />
                     <conditions>
                         <add input="{URL}" pattern="(.*)\/umc-sso(.*)" />
                     </conditions>
                     <serverVariables>
                         <set name="HTTP_COOKIE" value="{HTTP_COOKIE};ReverseProxyHost={HTTP_HOST};ReverseProxyPort={SERVER_PORT}" />
                     </serverVariables>
                     <action type="Rewrite" url="http://localhost:8443/umc-sso{C:2}" />
                 </rule>  
             </rules>
     </rewrite> 
...

More examples for rewrite rules

<rewrite>
    <rules>
        <rule name="Reverse Proxy to webmail" stopProcessing="true">
            <match url="^webmail/(.*)" />
            <action type="Rewrite" url="http://localhost:8081/{R:1}" />
        </rule>
        <rule name="Reverse Proxy to payroll" stopProcessing="true">
            <match url="^payroll/(.*)" />
            <action type="Rewrite" url="http://localhost:8082/{R:1}" />
        </rule>
    </rules>
</rewrite>

Restart site with “Internet Information Services (IIS) Manager”