Hi Seoyeon Lee,
Windows services fail to detect proxy settings because they run in an isolated system session, unable to access the user-specific registry keys where those settings are stored. To resolve this, you must either configure the proxy globally at the machine level using the netsh winhttp set proxy command, which allows the system to communicate directly with the proxy, or explicitly define the proxy within your application's appsettings.json and inject it into your HttpClientHandler. Both methods bypass session-dependent constraints to provide stable, enterprise-grade connectivity for your background service.
VPHAN