As I said on the gnome bugzilla compiling both server and client with --enable-ipv6=yes solve the problem.
** Summary changed: - XDMCP not working + XDMCP not working in ipv6, gdm should be compiled with --enable-ipv6=yes -- XDMCP not working in ipv6, gdm should be compiled with --enable-ipv6=yes https://launchpad.net/bugs/75254 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
