Create second VIP for new application / not able to get to application

Without knowing more about the static config of BIG-IP, 8443 is used for BIG-IP management access (versions after 12.1). Public IP does not equal elastic IP so if we are just using the public DNS using NAT gateways, then you may be using the self IP for the applicaiton access. If we are talking about different IP's from what BIG-IP is using for it's self IP then I suspect traffic isn't making it to the BIG-IP interface.

If you look at the VIP statistics tab, you'll see if any traffic is hitting that address. I suspect there may be some security group requirements that still need to be setup for 8443 from the elastic IP (you're using elastic for the public access correct?).

Can you provide some more details around the IP configurations within BIG-IP and how the security groups are configured around the incoming traffic through the elastic IP that translates to your BIG-IP?