Re: Dealing with ICMPv6 network unreachable.

[Martin Husemann <martin%duskware.de@localhost>]

On Thu, Apr 02, 2015 at 08:58:01PM +0100, Roy Marples wrote:
> onto the IPv4 address which works fine. This is quite a fast operation.
> Other applications, such as ssh and firefox also have long stalls before
> falling back to IPv4 and again the fallback is quite prompt in Linux.

Firefox usually tries both connections in parallel ("Happy Eyeballs").
You can disable this by setting network.http.fast-fallback-to-IPv4 to
false in about:config, and you can completely disable v6 by
setting network.dns.disableIPv6 to false.

However, your description does not sound like connections are the real
problem, but more your DNS setup. Did the router provide a nameserver
with IPv6 address in the DHCP option?

Martin