temp_valid_lft

file: /proc/sys/net/ipv6/conf/interface/temp_valid_lft
variable: net.ipv6.conf.interface.temp_valid_lft
Official reference

valid lifetime (in seconds) for temporary addresses. Default: 604800 (7 days)

Nb: per interface setting (where “interface” is the name of your network interface); “all” is a special interface: changes the settings for all interfaces.

source