Hi Dave,
I highly suggest that you change port 80 to something else for port conflict and security reasons. Then access it just using
the DDNS address followed by the port with a colon separating them.
If you want my networking checklist that explains all of this, drop me a short mail to dj0qn (at) darc (dot) de and I will
send it to you.
73,
Mitch DJ0QN / K7DX