DHCPv6 PD ISP, Delegated /64 - RA not pushing default route

Installing and Using OpenWrt
1

Using OpenWrt-21.02 on X86. Have WAN_AA and WAN_AA_6 (Virtual dynamic interface (DHCPv6 client) running, able to ping IPv6 Addresses from router.

DHCP set up on lan as follows:

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Lan appears to have both ISP Delegated address on the /64 and its own SLAAC:
LAN
IPv4: 192.168.1.1/24
IPv6: 2001:FFF:HHH:GGG::1/64
IPv6: fdd9:xxx:yyy::1/60

LAN Clients also seem to be happily picking up addresses on both the 2001:...::/64 ISP delegated, and the fdd9 SLAAC, however they don't seem to be receiving 2001:FFF:HHH:GGG::1 as the default route. All works well if I add routes:

 ~  sudo ip -6 route add 2001:8b0:e1d:be61::1 dev enp7s0                                                                                                 
 ~  sudo ip -6 route add default via 2001:8b0:e1d:be61::1 
 ~  ping 2001:8b0:0:81::51bb:51bb                                                                                                                           ✔  14:17:28 
PING 2001:8b0:0:81::51bb:51bb(2001:8b0:0:81::51bb:51bb) 56 data bytes
64 bytes from 2001:8b0:0:81::51bb:51bb: icmp_seq=1 ttl=62 time=6.33 ms
64 bytes from 2001:8b0:0:81::51bb:51bb: icmp_seq=2 ttl=62 time=6.48 ms
^C
--- 2001:8b0:0:81::51bb:51bb ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 6.333/6.405/6.478/0.072 ms

Any ideas what I may be doing wrong to prevent the RA sending its address as the default route? Using MWAN3 for v4 traffic if it makes any difference, although would rather just ignore this for v6 (Have set a default V6 rule to go straight ahead and use the WAN_AA_6)

2

IPv6-PD clients will not get gateway?

3

Not sure this is it (un?)fortunately - AAISP seem to work straight off the bat with the EdgeRouter on Stock, so presumably working in that regard.

Is the RA from the OpenWrt acting as server dependent on the upstream ISP?

4

Yes. In particular see the ra_default option. Odhcpd will not advertise itself as router in RAs unless a default route and/or a public prefix is present. The default is option ra_default 0 which will announce OpenWrt as default router if OpenWrt itself has an IPv6 default route. Other potential values are 1 which announces a default router if a public prefix is present or 2 which always announces a default router, regardless of OpenWrt's own local IPv6 connectivity.

What's reported by ip -6 route show, ifstatus wan_aa_6 and ifstatus lan on OpenWrt?

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