Problem accessing site via Fortigate

Hi

REF: www.esafety.academy 

Fortigate: 3240C v5.2.7 

If I access the above site via mobile data (3G/4G) or a connection that is external to our site it works fine, however if I view the site internally via the fortigate then I just see the default apache server web page.  To me it looks like the Fortigate is blocking some sort of redirect that is taking place.

Any ideas as to what is causing the issue.

Thanks

Ian