Use static IPv6 suffix on wan6 configured with DHCPv6c

Installing and Using OpenWrt
1

i'm relatively new to ipv6.

my ISP is pppoe based, and they give me a static /56 prefix. (well, i think, but i cannot really verify this because logread doesn't contain anything ipv6 related when i ifdown wan && ifup wan... why?)

my desired outcome is to have my router be reachable on a fixed ipv6 address under my domain name (for wireguard configured with a domain name, not an ip address or dyndns).

so, what (i think) i need is a way to configure openwrt to assign a static ipv6 suffix on my wan6 interface.

what actually happens is that each time i ifdown wan && ifup wan i get an address with the same prefix, but a new, seemingly random suffix.

i tried to add ip6ifaceid ("IPv6 suffix" in luci), but sadly that didn't help:

config interface 'wan6'
        option device 'br-wan'
        option proto 'dhcpv6'
        option ip6ifaceid '::dead:beef'

ip a | grep -i dead comes back empty.

i tried to mess with /proc/sys/net/ipv6/conf/default/addr_gen_mode to no avail.

any hints on what concept i should understand, or what i should read?

i was unable to websearch this using "fixed ipv6 dhcp wan" and similar queries. i'm probably missing the right nomenclature.

2

If you have static wan address and static prefix, then why don't configure them as static?

3

i'm not 100% sure that i have a static prefix, and getting my domain out of sync is much less of a problem than losing ipv6 connectivity.

i was hoping that it's something trivial, but if it's not, then i'll just clarify with my provider and configure it as static.

4

Please take my following statement with a grain of salt.
Often the wan interface uses pppoe and therefore the wan6 interface gets only an address via dhcpv6 so ip6ifaveid isn't used.
But you can if you like add an alias interface and use i.e. ip6hint 0 on that alias interface together with your preferred ifaceid.