4D app with https via IIS reverse proxy not working

I am trying to set up a simple reverse proxy for http and https for a 4D app running on a windows server 2012 R2. I got http working but not https. When I open the public firewall and access the 4D app directly https is working fine. Could someone give me a hint of what I am doing wrong or what I need to do to also get https working?

This is what I did: I opened the ARR reverse proxy settings form for the main server and entered the following values: Enable Proxy Pass through Keep alive Timeout=120 X-Forwarded-For Include TCP port from client IP Memory cache duration=60s Enable disk cache Ignore query string Response buffer =4096 kb Threshold = 256 kb Use Url Rewrite to inspect incoming requests Reverse Proxy = DNSName:LocalHttpPort

After saving the ARR reverse proxy settings form, two URL-Rewrite Rules „ARR_server_proxy“ and „ARR_server_proxy_SSL“ were automatically created. All I needed to do was to fill in the field for the recoded URL. For the http Rule I entered: „http://DNSName:LocalHttpPort/{R0}“ For the https Rule I entered: „https://DNSName:LocalSSLPort/{R0}“

As I mentioned above these settings work for http. When I try https, I get a browser timeout. I read somewhere that I need to import the SSL-certificate + private key that I set up for the 4D app to IIS. I did this, but then I could not figure out how to bind it to the main server? And whether I need to set „Enable SSL offloading“ if I did this?

I also read somewhere else that I should enter in the Reverse Proxy field of the ARR reverse proxy settings form only the DNSName. I entered DNSName:LocalHttpPort. When I enter only the DNSName i get a Browser timeout. After reading dozens of contributions on this topic I got more and more confused.

here is the XML of the rewrite rules:(added 19.08.2021 14:00 MEZ)

<proxy enabled="true" />  
 <rewrite>  
     <globalRules>  
         <rule name="ARR_server_proxy_SSL" enabled="true" patternSyntax="Wildcard" stopProcessing="true">  
             <match url="*" />  
             <conditions>  
                 <add input="{HTTPS}" pattern="on" />  
             </conditions>  
             <action type="Rewrite" url="https://h25XXXXX.stratoserver.net:4443/{R:0}" />  
         </rule>  
         <rule name="ARR_server_proxy" enabled="true" patternSyntax="Wildcard" stopProcessing="true">  
             <match url="*" />  
             <action type="Rewrite" url="http://h25XXXXX.stratoserver.net:4000/{R:0}" />  
             <conditions>  
                 <add input="{HTTPS}" pattern="on" negate="true" />  
             </conditions>  
             <serverVariables>  
             </serverVariables>  
         </rule>  
     </globalRules>  
     <allowedServerVariables>  
         <add name="{HTTPS}" />  
     </allowedServerVariables>  
 </rewrite>