How to full-cone nat on CGNAT

Full-cone NAT has two ramifications: any packet from iIP:iPort is mapped to the same eIP:ePort, and any inbound flow/connection to eIP:ePort is forwarded to iIP:iPort. The first ramification is a natural side-effect of how the BIG-IP maps internal clients to a translation address+port. The second is accomplished by enabling inbound connections:

• SOL14823: Overview of CGNAT Persistence

Though the BIG-IP documentation about this is generally spare, F5 refers to this as Endpoint-Independent Filtering.

So, the short answer is: enable inbound connections as described in SOL14823.