Android 6.0 API 23:
I'm using java.net.Socket. I want to release the hostname: port binding so a client phone can: connect, crash so the app has to be restarted on the client phone, then reconnect to the same IP and port without restarting the server app. Is this possible or do I have to start a new server listening on a different port? I'm not using asynchronous communication. What I'm using is more old school.

What are you trying to achieve?

Even if you were to kill off the socket, reestablishing the same socket on the server end would make the connection very very broken.

so some server @ 192.168.1.10 listens on port 80 (192.168.1.10:80)

so some client @ 192.168.1.20 connects on a ephemeral port (192.168.1.10:10000-65336)

even if you were to break the socket on the server and reestablish the socket, the state of any connection would be in limbo. Because the server might have the right socket, but ultimately were its data is being sent won't be the correct port, so while clients can listen to the servers port 80, they won't be able to reply because in order to reestablish a connection to the server the client would need to open another ephemeral port and because there is no way the server can tell the client to do this your connection hangs in limbo. (until the client make another attempt to contact the server using a different ephemeral port and establishing a connection again.)

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