Issue Plesk 502 bad gateway (104: Connection reset by peer) while reading response header from upstream

[Busi]

After doing a clean install of my dedicated debian and a clean install of plesk i started getting error 502 bad gateway diffend places already at where i had to put in my license key but i got past that but now everytime i try and add a extension from either zip file or catalog i get it again. the sw-cp-server log shows


2016/10/10 04:41:58 [error] 13365#0: *557 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 2.104.126.106, server: , request: "POST /admin/module/install-from-catalog/uuid/f6847e61-33a7-4104-8dc9-d26a0183a8dd?_randomId=97162 HTTP/1.1", upstream: "fastcgi://unix:/var/run/sw-engine.sock:", host: "digfordiamonds.com:8443", referrer: "https://digfordiamonds.com:8443/admin/module/catalog"


I have already tried to increase
fastcgi_buffers 32 32k;
fastcgi_buffer_size 64k;

with no luck at all. and I'm lost on what to do

 

[Bitpalast]

Do you have fail2ban activated? Have you whitelisted localhost (127.0.0.1/8) and your public IPv4 address?