How to overwrite the AssertionConsumerURL in SAML2 request

[Peter Schober]

* Jesper <jesper.laursen at lego.com> [2018-08-30 07:44]:
> Shibboleth SP 2.6.

You're aware you're running old, unsupported software?

> The public address is "public.corp.com" and the EC2 IIS 10.0 instance is
> running on "internal.corp.com".
> The /secure is working when we in the Azure tell that the replyURL is
> "internal.corp.com" because that is what Sihb SP sends in the SAML2 Request.
> In fact all bindings are send as "internal.corp.com" and not
> "public.corp.com".

You'll need to set the publicly visible host name, the internal name
is irrelevant and will never work. With Apache httpd that's done using
the ServerName config directive, for IIS there's probably something in
the SP config that provides any missing features.
The documentation for SPv3 (which you're not using yet) is at
https://wiki.shibboleth.net/confluence/display/SP3/HowToRequestMap

-peter