Recently I put the latest firmware as mine was May 2013 vintage. Alas the connection was no longer stable, but seems that remoterig radio end that was crashing
After a while, perhaps an hour, on changing frequency the remote client front panel unit would go blank with a beep. The radio itself was still on and listening. On pressing the remote front panel back on it would be slower to connect, then no sound until you moved the rf gain back and forth. All would seem well until you changed frequency then it would crash again. Only restarting the TX/RX 1258 unit would the system be stable for a while.
Putting back the earlier firmware resolved this error.
By the way I have never experienced the YAESU 857D lockup that was clearly detailed in the manual. The connections stable and I never needed to reboot either the units nor 857D in weeks of operation in Antarctica. Delightful
