Feddit UK

I'm not sure if that's my server config or yours. But my PieFed instance over at palaver.p3x.de is having difficulties connecting to feddit.uk
I've narrowed it down to IPv6:

[root@galahad:~]# curl -v -H 'Accept: application/activity+json' "https://feddit.uk/c/buyeuropean"         
* Host feddit.uk:443 was resolved.  
* IPv6: 2a01:4f8:172:1f0d::2                                                                                                                                                                                        
* IPv4: 138.201.83.101  
*   Trying [2a01:4f8:172:1f0d::2]:443...  
* ALPN: curl offers h2,http/1.1  
* TLSv1.3 (OUT), TLS handshake, Client hello (1):  
* TLSv1.3 (IN), TLS handshake, Server hello (2):  
* TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):  
* TLSv1.3 (IN), TLS handshake, Certificate (11):  
* TLSv1.3 (IN), TLS handshake, CERT verify (15):  
* TLSv1.3 (IN), TLS handshake, Finished (20):  
* TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):  
* TLSv1.3 (OUT), TLS handshake, Finished (20):  
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384 / x25519 / RSASSA-PSS  
* ALPN: server accepted h2  
* Server certificate:  
*  subject: CN=feddit.uk  
*  start date: Jun 22 09:23:03 2025 GMT  
*  expire date: Sep 20 09:23:02 2025 GMT  
*  subjectAltName: host "feddit.uk" matched cert's "feddit.uk"  
*  issuer: C=US; O=Let's Encrypt; CN=R11  
*  SSL certificate verify ok.  
*   Certificate level 0: Public key type RSA (2048/112 Bits/secBits), signed using sha256WithRSAEncryption 
*   Certificate level 1: Public key type RSA (2048/112 Bits/secBits), signed using sha256WithRSAEncryption 
*   Certificate level 2: Public key type RSA (4096/152 Bits/secBits), signed using sha256WithRSAEncryption 
* Connected to feddit.uk (2a01:4f8:172:1f0d::2) port 443  
* using HTTP/2  
* [HTTP/2] [1] OPENED stream for https://feddit.uk/c/buyeuropean  
* [HTTP/2] [1] [:method: GET]  
* [HTTP/2] [1] [:scheme: https]  
* [HTTP/2] [1] [:authority: feddit.uk]  
* [HTTP/2] [1] [:path: /c/buyeuropean]  
* [HTTP/2] [1] [user-agent: curl/8.12.1]  
* [HTTP/2] [1] [accept: application/activity+json]  
> GET /c/buyeuropean HTTP/2  
> Host: feddit.uk  
> User-Agent: curl/8.12.1  
> Accept: application/activity+json  
> 
* Request completely sent off  
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):  
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):  
* HTTP/2 stream 1 was not closed cleanly: PROTOCOL_ERROR (err 1)  
* Connection #0 to host feddit.uk left intact  
curl: (92) HTTP/2 stream 1 was not closed cleanly: PROTOCOL_ERROR (err 1)  

From my home IPv4 internet connection it works fine. Also once I add an -4 to the curl, it succeds and returns a 200 and the response.

I've opened a bugreport for PieFed but I think we need to find out whether I or feddit.uk has a borked IPv6 config. I can connect to other instances just fine, so I'm gravitating towards there is some issue with feddit.uk

I'm sorry if this is the wrong place for support questions. Feel free to remove the post and point me somewhere else, or delete the post after this has been solved.