Hi @cloudBrett,
The documentation doesn’t explicitly state any config for IIS (it links to this tutorial instead). I think the solution Brian stumbled upon is that HTTP headers in web.config need to be prefixed with HTTP_.
So, probably you would need something like:
<serverVariables>
<set name="ORIGINAL_URL" value="{HTTP_HOST}" />
<set name="HTTP_X_FORWARDED_PROTO" value="https" />
<!-- Also maybe this one ? <set name="HTTP_X_FORWARDED_FOR" value="{HTTP_HOST}" /> -->
</serverVariables>
Let us know if that helps.