Creating a new self-signed SSL device certificate in BIG-IQ version 4.5

https://support.f5.com/kb/en-us/solutions/public/k/52/sol52425065.html

The article mentioned above works great but take note that the certificate and the key have to be placed into different directories. Also, you can use any Big-IP to generate the CSR and private key by navigating to System; File management; SSL Certificate List