WHS username.homeserver.com works but IP does not

Ok so this no longer makes sense to me so I figured I would ask.

I have a windows home server which is has a static DHCP mapping as WHS to 192.168.1.XX. I configured DNAT as:

Traffic selector:Any, → HTTPS → External (WAN) (Address)

Destination translation:
WHS > HTTPS

Automatic Firewall rule: X
Initial packets are logged: X

I can get to https://username.homeserver.com from external but I cannot using the external ip as https://70.189.***.*** . https://username.homeserver.com resolves to the 70.189.***.*** IP.

What am I missing here?