Understanding Connection Reset by peer

Connection reset by peer means the TCP stream was abnormally closed from the other end. 

A TCP RST was received and the connection is now closed.

This occurs when a packet is sent from our end of the connection but the other end does not recognize the connection; 

it will send back a packet with the RST bit set in order to forcibly close the connection.

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“Connection reset by peer” is the TCP/IP equivalent of slamming the phone back on the hook. 

It’s more polite than merely not replying, leaving one hanging. 

But it’s not the FIN-ACK expected of the truly polite TCP/IP.