You cannot modify the TLS/SSL protocol version. The HTTPS monitor will choose the highest level TLS/SSL protoco
, according to
K16526: Configuring the SSL cipher strength for a custom HTTPS health monitor.
It is more likely that your back-end server does not accept higher versions of SSL/TLS protocol. You can check the supported version of that server by running the following on BIG-IP:
openssl s_client -tls1 -connect x.x.x.x:443
You can also use other flags when checking:
-ssl2, -ssl3, -tls1, -tls1_1, -tls1_2, -no_ssl2, -no_ssl3, -no_tls1, -no_tls1_1, -no_tls1_2
to find out exactly what is supported there.