ipv6 prefix

I use ASUS router for dialing. According to the log information, the ISP seems to assign a prefix of /60, but the prefix of router and ppp0 is /64. I made some attempts but could not configure a shorter prefix. dhcp6_client: WAN Prefix Size Requested:/60, Received:/60 dhcp6_client: bound prefix...

Hi, I would like to configure a static local IPv6 address prefix (as defined by RFC 4193 Unique Local IPv6 Unicast Addresses) on my RT-AC87U router using Asuswrt-Merlin. After looking at the documentation, I cannot find a way to do that. Any idea? I already enabled SSH connection if that is...