IIS 10.0 Reverse Proxy with ARR and URL rewrite causing ERR_TOO_MANY_REDIRECTS only on HTTP

Question

I have an IIS server hosting a few external domains and also an internal web app, also I have a woocommerce site sitting on an apache server. The IIS server sits on a fixed public IP address and the Apache server also on another fixed public IP. All infrastructure is in house. We are shortly giving up out /29.network for a single fixed IP /32.network. I was planning to use ARR and URL rewrite to have both the IIS and Apache server utilize 1 fixed public IP.

I installed ARR on the IIS box and configured the following web.config, note that bost the IIS box and Apache box have valid certificates.

<configuration>
    <system.webServer>
        <rewrite>
            <outboundRules>
                <rule name="ReverseProxyOutboundRule1" preCondition="ResponseIsHtml1">
                    <match filterByTags="A, Form, Img" pattern="^http(s)?://192.168.8.100/(.*)" />
                    <action type="Rewrite" value="http{R:1}://test.example.com/{R:2}" />
                </rule>
                <preConditions>
                    <preCondition name="ResponseIsHtml1">
                        <add input="{RESPONSE_CONTENT_TYPE}" pattern="^text/html" />
                    </preCondition>
                </preConditions>
            </outboundRules>
            <rules>
                <clear />
                <rule name="ReverseProxyInboundRule1" stopProcessing="true">
                    <match url="(.*)" />
                    <conditions>
                        <add input="{CACHE_URL}" pattern="^(https?)://" />
                    </conditions>
                    <action type="Rewrite" url="{C:1}://192.168.8.100/{R:1}" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

192.168.8.100 being the internal server hosting woocommerce on Apache. So what works after this is that https://test.example.com works fine reverse proxied to appache from IIS, test.example.com also works fine. However http://test.example.com fails with ERR_TOO_MANY_REDIRECTS which I can see using fidler.

Things I have tried

Turning off 'Reverse rewrite host in response headers' in ARR, this stops the too many redirects but shows the host as the 192.168.8.100 address and obviously fails the cert, however woocommerce site comes up fine.

Adding a rewrite rule for HTTP to HTTPS to Apache at /etc/apache2/sites-available/wordpress.conf - This made no difference to the too many redirects error.

Adding a redirect rule for HTTP to HTTPS in the .HTACCESS file at /var/www/wordpress/.htaccess - This made no difference to the too many redirects error.

Remove Really Simple SSL plugin from Wordpress - This made no difference to the too many redirects error.

I am now at my wits end as to what to try now.

Answer 1

Answering my own question, and it was a schoolboy error, when I tried the IIS HTTP --> (HTTPS) rewrite, I forgot to move it up ahead of the reverse proxy rule, hence it was never, ever going to execute it. Move it up and all works fine. Doh!