I had a similar issue on Windows 11 trying to route my IP address to localhost development environment. Certificate validation was causing my issue.

https://learn.microsoft.com/en-us/iis/extensions/configuring-application-request-routing-arr/arr-support-added-for-winhttpoptionsecurityflags

I short, if you modify the following registry entry, it will ignore the SSL connection issue

reg.exe add "HKLM\SOFTWARE\Microsoft\IIS Extensions\Application Request Routing\Parameters" /v SecureConnectionIgnoreFlags /t REG_DWORD /d 0x00003300

Not something you want for production, but works great for development environment.