To check the minimum memory, disk space, and other system requirements for installing the Oracle Solaris 11.4 release, see Oracle Solaris 11.4 Release Notes.
Make sure that your system's firmware is updated to the latest version before installing Oracle Solaris 11.4. See https://www.oracle.com/technetwork/systems/patches/firmware/index.html.
On SPARC systems, the firmware must be updated to include the current version of the Open Boot PROM (OBP) that contains the latest WAN boot support.
# eeprom | grep network-boot-arguments network-boot-arguments: data not available
If the variable network-boot-arguments is displayed, or if the command returns the output network-boot-arguments: data not available, the SPARC system's OBP supports WAN boot. Otherwise, you must use alternatives such as using media. See Automated Installations That Boot From Media.