Forwarded port still shows filtered

I setup port forwarding via the Xfinity website.  The port is forwarded to the correct internal IP address on my network.  I have a website on that port on that server that I use so others I work with can see changes I'm making to the next version of the production website.  I cannot access it from the external IP address.  I went to a website that checks port forwarding.  That site shows the port as filtered and lists the service as unknown.  Any ideas what I might be doing wrong?