Good point @Uberseehandel .   Here in Belgium our providers use a router-modem-combo to terminate the connections, so that isn't so much an issue. V4 or v6 doesn't matter anymore then.   My MX just has a private v4 IP on its WAN side and I have the MX defined as "DmZ host" in the provider router, which basically forwards all traffic to the MX. But this all depends on how the providers work I guess. ... View more