Sending files via a cron to S3, the files send but the TCP buffer fills up and does not clear/empty which causes chaos with the server services.
this is the line in plesk panel (like in the other post): tcpsndbuf 2,712,477 2,867,477 bytes Total size of buffers used to send data over TCP network connections
in the plesk help i found (virtuozzo section): tcpsndbuf is the total size of send buffers for TCP sockets, i.e. the amount of kernel memory allocated for the data sent from an application to a TCP socket, but not acknowledged by the remote side yet