Opening port with IP tables and UFW doesn't appear to open port

I have attempted to open port 443 on a server I'm working on (Ubuntu 16.04):

/sbin/iptables -I INPUT -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT

The port doesn't appear to be open:

nmap cubicverse.com

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:https state NEW,ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:433 state NEW,ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere             state NEW tcp dpt:https

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination 

I have also opened the port with ufw.

What alternative steps may be needed to open the port?

To be clearer, I am attempting to add an SSL cert for this server, and the 'SSL checker' keeps telling me I have a closed port and hence it can't validate the CSR.