Re: GNU Elpa not reachable (possibly OT)

[Robert Pluim]

Joost Kremers <joostkremers@fastmail.fm> writes:

> Hi all,
>
> The past few days I've been having trouble updating my packages, which
> turns out to be caused by Emacs not being able to reach
> <https://elpa.gnu.org>. The problem isn't that the server is down (it
> isn't), but I'm not entirely sure what the problem is, so I thought
> I'd post here, in case anyone can help, even though it may not be an
> actual Emacs problem...
>
> Trying to refresh my package list results in the following error:
>
> error in process filter: Error retrieving:
> https://elpa.gnu.org/packages/archive-contents (error http 400)

Do you get this error straight away, or after a timeout?

> Funny thing is, I can paste that URI in the address bar of my browser
> and the file loads just fine. 
>
> Looking at this reddit page:
>
> https://www.reddit.com/r/emacs/comments/arnbhb/cant_reach_elpa_for_the_last_couple_of_days/
>
> I tried the same thing as in one of the posts there, and indeed,
> `nslookp elpa.gnu.org` gives me:
>
>
> ```
> Non-authoritative answer:
> Name:   elpa.gnu.org
> Address: 209.51.188.89
> Name:   elpa.gnu.org
> Address: 2001:470:142:5::89
> ```
>
> and then `ping elpa.gnu.org` yields:
>
> ```
> PING elpa.gnu.org(2001:470:142:5::89 (2001:470:142:5::89)) 56 data
> bytes
> From 2001:470:142::1 (2001:470:142::1) icmp_seq=1 Destination
> unreachable: Address unreachable
> ```

Any chance of you running tcpdump or wireshark to capture what traffic
Emacs is sending?

> Several IPv6 test sites tell me my IPv6 connectivity is fine, except
> for one, which states that "Your router or firewall is filtering
> ICMPv6 messages sent to your computer."
>
> So I'm wondering if that may be the cause of the problem and if yes,
> what can I do about it?

You may have a not-quite-working IPv6 setup, which is causing Emacs to
try to connect via IPv6 and failing rather than falling back to IPv4.

Could you let us know which version of Emacs this is? Also that
network trace would be *really* useful.

Thanks

Robert