pfSense

if the usb 3g/4g modem is unplugged then reconnected or itself rebooted (via AT commands) it comes up as ttyU1 (aka cuaU1) then ttyU2 (aka cuaU1) etc after which the pfsense config cant reconnect

ttyU0.{0,1,2} (aka cuaU0.X) all disappear but ttyU0.3 (aka cuaU0.3) remains. i think this is why the kernel gives it the next ttyU (aka cuaU) spot

the result of the above is that pfsense is configured for cuaU0 (aka ttyU0) it cannot reconnect and must be reconfigured (which breaks again on reboot) or rebooted.

i found that this is due to /usr/local/bin/3gstats.php holding open the cuaU0.3 device which stops it from clearing and being available when the usb is plugged in again. ssh'ing into pfsense, killing the running 3gstats.php, then replugging the device then works perfectly.

it seems that /usr/local/bin/3gstats.php should be listening for the HANGUP signal and then exiting gracefully when received, observe how the 'cu' command exits gracefully if youre connected to the cuauU0.X and you pull out the USB.

cu -l cuaU0.3