1- set IP@ and name-sever
2- test internet connectivity + domain name resolution
3- copy the file to the local directory /var/tmp/
4-
set system name-server 8.8.8.8
file copy "https://cdn.juniper.net/xxxxxxx/jinstall-ppc-18.4R1.8-signed.tgz?/xxxxx /var/tmp/jinstall-ppc-18.4R1.8-signed.tgz
request system software validate /var/tmp/jinstall-ppc-18.4R1.8-signed.tgz
request system software add /var/tmp/jinstall-ppc-18.4R1.8-signed.tgz
request system reboot