I’m testing IPv6 on a corporate network and having problems with OS X. With most IPv6 commands, such as telnet -6 or traceroute6, I get the error:

connect: No route to host

For example, I have a web server. This fails:

$ telnet -6 fe80::… 80    # this fails

I know the server is reachable because ping6 works (note that I have to use the -I argument):

$ ping6 -I en1 fe80::…    # this works

And I know the web server is running because I can telnet to it from Windows:

C:\> telnet fe80::… 80  # this works

I suspect there is some configuration flag or command-line argument that I am missing.