Issue Bad Gateway - nginx - IPv6 only

[Powie]

Server operating system version

U22

Plesk version and microupdate number

Latest

Only on one Server, we are facing the issue that No Sites are reachable by IPv6. Theres the upstream Error in the logs. No Idea why..

We tried the plesk repair tool and also checked fail2ban but got No Idea.
IT works on Pages with nginx only settings, but Not for default Setups with nginx/Apache .

Any recommendations what to Check next?

 

[PAM Baduijn]

Try to add these rules to the Nginx domain options:

proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;

 

[Powie]

Try to add these rules to the Nginx domain options:

proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;

doesn't help... also exist on docker port forwards by ipv6. investigating more n ngnx config now