Specifies the name of the curve to use in ECDH key exchange. It needs to be supported by all clients that connect. It does not need to be the same curve used by the server's Elliptic Curve key. This parameter can only be set in the postgresql.conf file or on the server command line. The default is
OpenSSL names for the most common curves are:
prime256v1 (NIST P-256),
secp384r1 (NIST P-384),
secp521r1 (NIST P-521). The full list of available curves can be shown with the command openssl ecparam -list_curves. Not all of them are usable in TLS though.
According to your SSL configuration, which maybe provided by your installer.