-In modern versions of PuTTY, you should not see this error.
-
-Windows's documentation about this error condition is not very good,
-but as far as we can tell, this error occurs when PuTTY is listening
-on a port, another program makes a connection to that port, but
-closes the connection so fast that PuTTY has no time to answer it.
-
-PuTTY only ever listens on a port when it is doing local-to-remote
-port forwarding (see \k{using-port-forwarding}); and if an incoming
-connection on that port receives this error, PuTTY should simply
-close the connection and continue without error.
-
-If you see this error in PuTTY 0.53 or above, we would welcome a
-report of the circumstances.
+This is a generic error produced by the Windows network code when it
+kills an established connection for some reason. For example, it might
+happen if you pull the network cable out of the back of an
+Ethernet-connected computer, or if Windows has any other similar
+reason to believe the entire network has become unreachable.
+
+Windows also generates this error if it has given up on the machine
+at the other end of the connection ever responding to it. If the
+network between your client and server goes down and your client
+then tries to send some data, Windows will make several attempts to
+send the data and will then give up and kill the connection. In
+particular, this can occur even if you didn't type anything, if you
+are using SSH-2 and PuTTY attempts a key re-exchange. (See
+\k{config-ssh-kex-rekey} for more about key re-exchange.)
+
+(It can also occur if you are using keepalives in your connection.
+Other people have reported that keepalives \e{fix} this error for
+them. See \k{config-keepalive} for a discussion of the pros and cons
+of keepalives.)
+
+We are not aware of any reason why this error might occur that would
+represent a bug in PuTTY. The problem is between you, your Windows
+system, your network and the remote system.