Yes it is, highest rule. No traffic is hitting the rule at all, even when 6in4 is working. (I have to disable the wan6 interface and set the default rules to family ipv4 in mwan3 for that though). iptables shows no packets or bytes on the rule when it's active.
At this point I'm going to have to give up with trying to handle IPv6 through mwan3 and just live with it for now, works fine for IPv4, it will have to do. Perhaps it's better if wan6 was native IPv6, maybe less complexity here, but I'm not expert enough and I've been messing around with for the past few days.
I'll revisit it at some point, I've stared at too many config files lately, going crazy!
ping -I 2001:470:xxxxx:xx::2 -c 3 2001:4860:4860::8888
PING 2001:4860:4860::8888 (2001:4860:4860::8888) from 2001:470:xxxx:xx::2: 56 data bytes
64 bytes from 2001:4860:4860::8888: seq=0 ttl=58 time=37.825 ms
64 bytes from 2001:4860:4860::8888: seq=1 ttl=58 time=21.830 ms
64 bytes from 2001:4860:4860::8888: seq=2 ttl=58 time=20.996 ms
--- 2001:4860:4860::8888 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 20.996/26.883/37.825 ms
This leads back to the original issue issue with my other wan interface, OpenWrt does not seem to be able to correctly use the source address in some cases, hence the weird behaviour, that's what I've found anyway.
However, installing ping6 from iputils-ping6, pinging the interface name 6in4-wan6 works, but because mwan3 using ping and not ping6 even with the iputils-ping version, this just throws "ping: unknown host 2001:4860:4860::8888"