Port 443

I have portforwarding set up on port 443 and 8123.  They were set up through the xfinity website.  Port 8123 tests fine and works the way i expect it, but when I test the port 443, the connection is repeatedly refused.   I have restarted my router but the portforwarding is still unsuccessful.  I'm using the router I received from xfinity when I set up my internet.

  What is going on with port 443 and what needs to happen for portforwarding to be successful on port 443?