GNU Elpa not reachable (possibly OT)

[Joost Kremers <joostkremers@fastmail.fm>]

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)

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
```

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?

Thanks,

Joost


-- 
Joost Kremers
Life has its moments