Re: Broken IPv6 / IPv4 configuration, or Gmail brokenness?

[Tim Woodall <debianuser@woodall.me.uk>]

On Mon, 23 Jan 2023, Celejar wrote:

> Thank you - the plot thickens. I tried radvdump, and I was indeed
> receiving IPv6 advertisements. I inspected my router (an OpenWrt box)
> more carefully, and lo and behold, the router *thinks* that it has IPv6
> connectivity: it reports that it has configured its WAN interface via
> DHCPv6, that it has an IPv6 prefix delegation (a /56), and that it has
> accordingly handed out an IPv6 address via DHCPv6 to my Debian system
> (which indeed shows having its network interface configured with that
> address). The problem is that IPv6 is not actually working at all:
> ping6 to IPv6 hosts, even from the router itself, get no response, and
> traceroute to IPv6 hosts show replies from only the first two hops, and
> just asterisks afterward.
>
> My ISP is notoriously cagey about the details of its (slow and
> incremental) IPv6 rollout. I suppose I can try customer service, but in
> the meantime, I just don't know whether I have a misconfiguration on the
> router, or whether the ISP is not actually providing working IPv6.

Does ping/traceroute work in ipv4?

It's depressingly common to find people who block icmp for 'security
reasons'. While you can mostly get away with that in ipv4, ipv6 breaks
catastrophically without at least some working icmp.

Also try tcptraceroute - although if some router is configured to drop
all icmp then I don't think ipv6 can work at all