My OpenWRT router sends all IPv4 traffic to a Wireguard VPN hosted in GCP.
Sadly, the GCP instance does not have global IPv6
Since the 6in4 traffic is also sent via the VPN, my OpenWRT router cannot setup the 6in4 connection once the VPN is setup.
I assumed this was because the VPN server was not forwarding Protocol 41 traffic back to the router. I see traffic sent on OpenWRT's 6in4 interface but 0 received.
On the VPN server I tried (to no effect):
iptables -A INPUT -p 41 -j ACCEPT
iptables -A PREROUTING -t nat -p 41 -d $VPN_PUBLIC_IP -j DNAT --to-destination 192.168.1.10 # OpenWRT router internal IP
How can I get this working via the VPN?