TN5250 data stream issues -- none of this makes any sense!

Cross-posted to the Midrange and Java Lists

None of this is making any sense. There's got to be something I'm not seeing:

We have a situation, on several customer boxes, in which the official IBM emulator, whatever they're calling it this week, is working fine, but our TN5250 client is constantly crapping out, sometimes without staying up long enough to sign on.

In our emulator, we have a thread that monitors, reads, and buffers the incoming data stream from the socket. There is a line of code that adjusts the socket timeout, depending on whether or not a data stream has been successfully processed on it at least once.

The socket is an SSL socket, at least in the cases I'm immediately looking at.

And for no apparent reason, it loses the socket: the aforementioned read gets an EOF, any write to the socket gets a broken pipe, and the line of code that adjusts the timeout gets this Java stacktrace:

19 Nov 2019 11:02:17:java.net.SocketException: Socket Closed
at java.net.AbstractPlainSocketImpl.setOption(AbstractPlainSocketImpl.java:212)
at java.net.Socket.setSoTimeout(Socket.java:1141)
at sun.security.ssl.BaseSSLSocketImpl.setSoTimeout(BaseSSLSocketImpl.java:631)
at sun.security.ssl.SSLSocketImpl.setSoTimeout(SSLSocketImpl.java:2526)

. . .

Or if I comment out the line that adjusts the timeout, then the stacktrace I get is:

19 Nov 2019 11:44:03:javax.net.ssl.SSLException: Connection has been shutdown: javax.net.ssl.SSLException: java.net.SocketException: Broken pipe (Write failed)
at sun.security.ssl.SSLSocketImpl.checkEOF(SSLSocketImpl.java:1541)
at sun.security.ssl.AppInputStream.read(AppInputStream.java:95)

. . .

The most frustrating part about this is that under what appear to be the same conditions, the official IBM emulator (which I understand to now be every bit as Java-based as ours) keeps on going as if nothing had ever gone wrong!

Could this have anything to do with any of the issues raised in the "5250 sessions killing the system" thread? Specifically, all that talk of the IBM emulator automatically reconnecting?

--
JHHL