[atlas] Probe doesn't seem to automatically recover from IPv6 connectivity failure

* Daniel Karrenberg

> Thank you for letting us know and also for speaking up to let us know
> this happens to more than one of you. We will look at this after the
> holiday weekend. In the meantime it would help to know the type of
> the routers and details about your IPv6 routing configuration.

FYI, in case you want to debug this problem present on a live probe, it
appears to be the case for probe 121 at the moment. It's connected
behind an AVM Fritzbox using SLAAC. No other devices connected to it
have a similar problem.

The probe should have had the IPv6 address
2a02:fe0:cf16:70:220:4aff:fec6:cd7a (which actually shows up on the
probe's web page), but it does not respond to anything - not to ICMPv6
NS from the local link to the aforementioned address, nor to
fe80::220:4aff:fec6:cd7a. No responses from its link-local address is
seen when pinging ff02::1 either. All the default measurements says
"Cannot send".

If you have no use for this debugging opportunity, let me know and I'll
reboot the probe and see if its IPv6 connectivity comes back then.

Tore