That article talks about "Configuring a 6to4 tunnel" while they clearly mean a 6in4 tunnel. While a 6to4 tunnel builds upon a 6in4 tunnel (well, proto-41) and are related it shows that the author of that article has no clue about the differences of these two protocols, which is rather important because they are configured quite differently. (6in4 needs both endpoints defined, 6in4 has own address space, 6to4 uses a deprecated anycast address etc) You thus just have to mentally replace all instances of "6to4" with "6in4" in that article. Nevertheless, as you are not providing any details of what you actually have entered in those fields, the first thing to keep in mind is that that thing apparently only supports static 6in4 tunnels, hence do make sure your tunnel type is set to that, and of course that you actually have a static endpoint.

Hello Jeroen Massar, I use a static IPv4 (Your IPv4Static, currently xx.xxx.xxx.xxx). In "Interface - X0 for IPv6" I entered Your IPv6 (2001:xxxx:xxxx::2). In "Creating IPv4 and IPv6 address objects" I entered "pop IPv4" (78.35.24.124), "PoP IPv6" (2001:xxxx:xxxx::1) and "All IPv6" (::/0). Everything else as the contribution described. Among the local computers the IPs is from SonicWALL DHCP assigned correctly, but external can not ping be answered via IPv6.