BIG-IP Oauth Client and AS

I was able to resolve the issue. Everything worked as expected on the BIG-IP side. As you mentioned, the BIG-IP was not able to get a token from itself (AS on the same BIG-IP) (token request through after DNS resolve to a public ip), the issue was located in our firewall construct, as I had to build a policy from internal to access the public IP which was also provided by the same firewall.