I have a subdomain (subdomain.domain.com) for which I need a certification. The files for this subdomain are in the Default Web Site of IIS 7.5 and are accessible on a different port than 80. I have stopped the Firewall totally but when I use the Test the first 2 steps are ok but at the end throws:
Could not verify URL is accessible: http://subdomain.domain.com/.well-known/acme-challenge/configcheck
Note that on the router I have NAT only on the port concerned and not on the 80. Do I have to do that too?