If you want to do a http(s) call per httpclient to an external destination in a Asp.NET Application on ionos webhosting you have to use a proxy server. Otherwise you’ll get a timeout of connection trial after a while with the following error message:
System.Net.Http.HttpRequestException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
The url of the internal win proxy is http://winproxy.server.lan:3128 to allow http(s) access to external destinations.
Link to ionos entry in help documentation: