Postgres could not receive data from client: Connection timed out
A few possibilities:


Your application closes connections without telling the PostgreSQL server it's doing so, by simply closing the network socket. It should send a PQclose(conn) if using libpq, or whatever equivalent your language/driver has.
Network address translation timeouts on idle connections or other related network issues cause the TCP connections to break, so client and server lose communication with each other.
A firewall on the client or server is blocking or disrupting connections after they're established (maybe malfunctioning IDS?)