I've upgraded to @hnyman's R7800-specific builds ( Build for Netgear R7800 - OpenWrt SNAPSHOT r14389-920d975cab ), and ensured that the newly generated config has both wan and wan6 in the wan zone (thanks @vgaetera and @trendy ), but without success.
# on router
root@OpenWrt:~# ping -c2 openwrt.org
PING openwrt.org (139.59.209.225): 56 data bytes
64 bytes from 139.59.209.225: seq=0 ttl=47 time=299.155 ms
64 bytes from 139.59.209.225: seq=1 ttl=47 time=261.898 ms
--- openwrt.org ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 261.898/280.526/299.155 ms
root@OpenWrt:~# ping6 -c2 openwrt.org
PING openwrt.org (2a03:b0c0:3:d0::1af1:1): 56 data bytes
64 bytes from 2a03:b0c0:3:d0::1af1:1: seq=0 ttl=40 time=259.040 ms
64 bytes from 2a03:b0c0:3:d0::1af1:1: seq=1 ttl=40 time=254.167 ms
--- openwrt.org ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 254.167/256.603/259.040 ms
# on LAN client
$ curl -4 openwrt.org
<html>
...
</html>
$ ping -4 -c2 openwrt.org
PING openwrt.org (139.59.209.225) 56(84) bytes of data.
64 bytes from wiki-01.infra.openwrt.org (139.59.209.225): icmp_seq=1 ttl=46 time=286 ms
64 bytes from wiki-01.infra.openwrt.org (139.59.209.225): icmp_seq=2 ttl=46 time=266 ms
--- openwrt.org ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 266.449/276.047/285.645/9.598 ms
$ curl -6 openwrt.org
curl: (7) Couldn't connect to server
$ ping -6 -c2 openwrt.org
ping: connect: Network is unreachable
New configuration files:
/etc/config/dhcp:
config dnsmasq
option domainneeded '1'
option boguspriv '1'
option filterwin2k '0'
option localise_queries '1'
option rebind_protection '1'
option rebind_localhost '1'
option local '/lan/'
option domain 'lan'
option expandhosts '1'
option nonegcache '0'
option cachesize '1000'
option authoritative '1'
option readethers '1'
option leasefile '/tmp/dhcp.leases'
option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
option nonwildcard '1'
option localservice '1'
config dhcp 'lan'
option interface 'lan'
option start '100'
option limit '150'
option leasetime '12h'
option dhcpv6 'server'
option ra 'server'
option ra_slaac '1'
list ra_flags 'managed-config'
list ra_flags 'other-config'
config dhcp 'wan'
option interface 'wan'
option ignore '1'
config odhcpd 'odhcpd'
option maindhcp '0'
option leasefile '/tmp/hosts/odhcpd'
option leasetrigger '/usr/sbin/odhcpd-update'
option loglevel '4'
/etc/config/firewall/:
config defaults
option syn_flood '1'
option input 'ACCEPT'
option output 'ACCEPT'
option forward 'REJECT'
config zone
option name 'lan'
list network 'lan'
option input 'ACCEPT'
option output 'ACCEPT'
option forward 'ACCEPT'
config zone
option name 'wan'
option input 'REJECT'
option output 'ACCEPT'
option forward 'REJECT'
option masq '1'
option mtu_fix '1'
list network 'wan'
list network 'wan6'
config forwarding
option src 'lan'
option dest 'wan'
config rule
option name 'Allow-DHCP-Renew'
option src 'wan'
option proto 'udp'
option dest_port '68'
option target 'ACCEPT'
option family 'ipv4'
config rule
option name 'Allow-Ping'
option src 'wan'
option proto 'icmp'
option icmp_type 'echo-request'
option family 'ipv4'
option target 'ACCEPT'
config rule
option name 'Allow-IGMP'
option src 'wan'
option proto 'igmp'
option family 'ipv4'
option target 'ACCEPT'
config rule
option name 'Allow-DHCPv6'
option src 'wan'
option proto 'udp'
option src_ip 'fc00::/6'
option dest_ip 'fc00::/6'
option dest_port '546'
option family 'ipv6'
option target 'ACCEPT'
config rule
option name 'Allow-MLD'
option src 'wan'
option proto 'icmp'
option src_ip 'fe80::/10'
list icmp_type '130/0'
list icmp_type '131/0'
list icmp_type '132/0'
list icmp_type '143/0'
option family 'ipv6'
option target 'ACCEPT'
config rule
option name 'Allow-ICMPv6-Input'
option src 'wan'
option proto 'icmp'
list icmp_type 'echo-request'
list icmp_type 'echo-reply'
list icmp_type 'destination-unreachable'
list icmp_type 'packet-too-big'
list icmp_type 'time-exceeded'
list icmp_type 'bad-header'
list icmp_type 'unknown-header-type'
list icmp_type 'router-solicitation'
list icmp_type 'neighbour-solicitation'
list icmp_type 'router-advertisement'
list icmp_type 'neighbour-advertisement'
option limit '1000/sec'
option family 'ipv6'
option target 'ACCEPT'
config rule
option name 'Allow-ICMPv6-Forward'
option src 'wan'
option dest '*'
option proto 'icmp'
list icmp_type 'echo-request'
list icmp_type 'echo-reply'
list icmp_type 'destination-unreachable'
list icmp_type 'packet-too-big'
list icmp_type 'time-exceeded'
list icmp_type 'bad-header'
list icmp_type 'unknown-header-type'
option limit '1000/sec'
option family 'ipv6'
option target 'ACCEPT'
config rule
option name 'Allow-IPSec-ESP'
option src 'wan'
option dest 'lan'
option proto 'esp'
option target 'ACCEPT'
config rule
option name 'Allow-ISAKMP'
option src 'wan'
option dest 'lan'
option dest_port '500'
option proto 'udp'
option target 'ACCEPT'
config rule
option name 'Support-UDP-Traceroute'
option src 'wan'
option dest_port '33434:33689'
option proto 'udp'
option family 'ipv4'
option target 'REJECT'
option enabled 'false'
config include
option path '/etc/firewall.user'
config include 'miniupnpd'
option type 'script'
option path '/usr/share/miniupnpd/firewall.include'
option family 'any'
option reload '1'
config include 'bcp38'
option type 'script'
option path '/usr/lib/bcp38/run.sh'
option family 'IPv4'
option reload '1'
and /etc/config/network:
config interface 'loopback'
option ifname 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'
config globals 'globals'
option ula_prefix 'fd69:4c0e:df8e::/48'
config interface 'lan'
option type 'bridge'
option ifname 'eth1.1'
option proto 'static'
option ipaddr '192.168.1.1'
option netmask '255.255.255.0'
option ip6assign '60'
config interface 'wan'
option ifname 'eth0.2'
option proto 'pppoe'
option username 'redacted'
option password 'redacted'
option ipv6 'auto'
config interface 'wan6'
option ifname 'eth0.2'
option proto 'dhcpv6'
config switch
option name 'switch0'
option reset '1'
option enable_vlan '1'
config switch_vlan
option device 'switch0'
option vlan '1'
option ports '1 2 3 4 6t'
config switch_vlan
option device 'switch0'
option vlan '2'
option ports '5 0t'