Need to configure specific Cipher "AES256-SHA256" in server SSL profile

I tested "AES256-SHA256" using openssl s_server against the end server.

I think technically you should be using openssl s_client to simulate the BIG-IP's role in communicating with the server. The client (BIG-IP) will send a list of ciphers that it can support to the server in its initial ClientHello message, and the server will pick a cipher from that list. That's generally how it works anyway. So if the client only presents one cipher, and the server supports that cipher, then that's what they will negotiate.