Hi there,
we use a fiber connection in germany, the provider (wemagcom) gives an IPv6/64 Prefix via DHCPv6-PD and IPv4 via CGNAT/Dual-Stack Lite (DSLite) - RFC2473.
Mikrotik becomes an IPv6/64 Prefix via DHCPv6-PD. Thats okay.
IPv4 works over in 4in6 Tunnel (DS-Lite) … the provider sends the FQDN Hostname of AFTR Gateway (CGNAT) via DHCPv6 Option 64 (OPTION_AFTR_NAME, RFC 6334) …
in our case is the hostname “aftr.aftr.local” and this resolve to an ipv6 Adress (2a03:b580:b000:1::1) of the AFTR Gateway-Server.
I want to send all ipv4 traffic in ipv6 tunnel to AFTR Gateway via Interface/IPIP6 Tunnel… the local IPv6 is one local IPV6 Adress of WAN interface and remote IPV6 Adress is the adress from AFTR gateway.
When i create a route under IP->Routes for 0.0.0.0/0 to interface ipip6-tunnel1 (tunnel name) then the gateway is unreachable. When i look under IPv6 → firewall → Connections a connection to AFTR is listed… but the status is : unreplied.
I think that is the problem… when the status were not unreplied, then will the route works i think…
under linux works it with follow commands:
ip tunnel add dslite1 mode ip4ip6 local [local ipv6-adress] remote [gateway aftr ipv6 adress]
ip l set dslite1 up
ip a add 192.0.0.1 dev dslite1
route add default gw 192.0.0.1
But under Mikrotik, i spend many days of time… not working. With other routers, for example EdgeRouter this works with follow commands:
configure
set interfaces ipv6-tunnel v6tun0 encapsulation ipip6
set interfaces ipv6-tunnel v6tun0 local-ip <<LOCAL IPv6 ADDRESS>>
set interfaces ipv6-tunnel v6tun0 remote-ip <<AFTR ADDRESS>>
set interfaces ipv6-tunnel v6tun0 mtu 1460
set protocols static interface-route 0.0.0.0/0 next-hop-interface v6tun0
commit
save
Can you help me please and integrate the function for automatic settings aftr gateway via dhcp option and create the tunnel after becomes an local ipv6 adress.
i mean this setup: https://wiki.tilde.fun/admin/network/cgnat
sorry for bad english. i hope you can understand 
best regards
marco