This has been an interesting bit of analysis.
The bottom line: both sides think that the other side went away. Calibre says that CC received a message then didn't respond correctly. CC says that it did respond to that message, then calibre simply disconnected.
My guess is that there was a "network event" that broke the connection. Possibilities in no particular order:
- Your device momentarily lost contact with your wifi router.
- Your device went to sleep (although CC tries to prevent this).
- Your machine running calibre momentarily lost contact with your network.
- A bug in Android's or your calibre machine's networking code that caused an empty packet to go from CC to calibre (this is unlikely).
- A bug in the client networking libraries that caused an empty packet to go from CC to calibre (also unlikely).
Thanks again for sending these logs to me. If nothing else I am learning where we need to improve logging.
BTW: you are not running the latest CC, V3.3.4. There aren't many changes between V3.3.3 and V3.3.4 so updating isn't urgent, but it is worth doing.