Thanks! "noprefixroute" works but "preferred_lft 0" does not. This is the whole config where preferred_lft has no affect: BOOTPROTO='static' STARTMODE='auto' IPADDR_1='192.168.1.111/24' IPADDR_2='fdcc:216f:1d2c::111/64' IPADDR_3='2003:a:xxxx:xxxx::111/64' IPADDR_4='fdcc:2222:1d2c::1/64' IP_OPTIONS_4='preferred_lft 0'