[this is an older event than reported on 10/27/23 around 10 AM PDT]

For some time now ssh connections to USB-serial devices
that provide serial console connections to a second Pi
have been dropping spontaneously.

With USB debugging enabled on the USB side the console
reports:

login: Oct 26 09:43:44 generic su[1200]: bob to root on /dev/pts/0
ucom_open: tp = 0xd6c3f400
ucom_cfg_open: 
ucom_dtr: onoff = 1
ucom_line_state: on=0x01, off=0x00
ucom_rts: onoff = 1
ucom_line_state: on=0x02, off=0x00
ucom_ring: onoff = 0
ucom_line_state: on=0x00, off=0x08
ucom_break: onoff = 0
ucom_line_state: on=0x00, off=0x04
ucom_status_change: 
ucom_param: sc = 0xd6c3f858
ucom_dtr: onoff = 1
ucom_line_state: on=0x01, off=0x00
ucom_rts: onoff = 1
ucom_line_state: on=0x02, off=0x00
ucom_ioctl: cmd = 0x402c7413
ucom_ioctl: cmd = 0x802c7416
ucom_status_change: 
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_ioctl: cmd = 0x2000740d
ucom_ioctl: cmd = 0x402c7413
ucom_ioctl: cmd = 0x802c7416
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_param: sc = 0xd6c3f858
ucom_ioctl: cmd = 0x8004667e
ucom_ioctl: cmd = 0x8004667d
ucom_get_data: cnt=0
ucom_outwakeup: sc = 0xd6c3f858
ucom_get_data: cnt=1
ucom_get_data: cnt=0
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400

On the ssh (which becomes the serial console of the
correspondent)side I see:
bob@generic:~ % su
Password:
# tip ucom
connected


FreeBSD/arm64 (pelorus.zefox.org) (ttyu0)

login: 

After several hours, the ssh end so the terminal
displaying serial console output reports:

login: client_loop: send disconnect: Broken pipe

Meanwhile the serial console of the USB end reports:

ucom_open: tp = 0xd6c3f400
ucom_cfg_open: 
ucom_dtr: onoff = 1
ucom_line_state: on=0x01, off=0x00
ucom_rts: onoff = 1
ucom_line_state: on=0x02, off=0x00
ucom_ring: onoff = 0
ucom_line_state: on=0x00, off=0x08
ucom_break: onoff = 0
ucom_line_state: on=0x00, off=0x04
ucom_status_change: 
ucom_param: sc = 0xd6c3f858
ucom_dtr: onoff = 1
ucom_line_state: on=0x01, off=0x00
ucom_rts: onoff = 1
ucom_line_state: on=0x02, off=0x00
ucom_ioctl: cmd = 0x402c7413
ucom_ioctl: cmd = 0x802c7416
ucom_status_change: 
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_ioctl: cmd = 0x2000740d
ucom_ioctl: cmd = 0x402c7413
ucom_ioctl: cmd = 0x802c7416
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_param: sc = 0xd6c3f858
ucom_ioctl: cmd = 0x8004667e
ucom_ioctl: cmd = 0x8004667d
ucom_get_data: cnt=0
ucom_outwakeup: sc = 0xd6c3f858
ucom_get_data: cnt=1
ucom_get_data: cnt=0
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_inwakeup: tp=0xd6c3f400
ucom_close: tp=0xd6c3f400
ucom_shutdown: 
ucom_dtr: onoff = 0
ucom_line_state: on=0x00, off=0x01
ucom_rts: onoff = 1
ucom_line_state: on=0x02, off=0x00
ucom_cfg_close: