No serial output (no replies)

I gave up on one of my GoFlex Home docks a few months ago because nothing was being output to the serial connection... Now after revisiting it, I see that the green LED has stopped flashing and become steady. My DHCP server indicated it was online, and I've just managed to ssh in.

Is there any way I can find out why it isn't outputting to the serial port?

I want to get back to my GoFlex Home FreeBSD project which stalled a while ago.

The current state of the dock is:-

root@debian:~# uname -a
Linux debian 4.12.1-kirkwood-tld-1 #1 PREEMPT Sat Jul 15 21:40:50 PDT 2017 armv5tel GNU/Linux

fw_printenv:-

bootcmd_exec=run load_uimage; if run load_initrd; then if run load_dtb; then bootm $load_uimage_addr $load_initrd_addr $load_dtb_addr; else bootm $load_uimage_addr $load_initrd_addr; fi; else if run load_dtb; then bootm $load_uimage_addr - $load_dtb_addr; else bootm $load_uimage_addr; fi; fi
bootcmd=run bootcmd_uenv; run scan_disk; run set_bootargs; run bootcmd_exec
bootcmd_uenv=run uenv_load; if test $uenv_loaded -eq 1; then run uenv_import; fi
bootdelay=10
bootdev=usb
device=0:1
devices=usb ide mmc
disks=0 1 2 3
ethact=egiga0
if_netconsole=ping $serverip
led_error=orange blinking
led_exit=green off
led_init=green blinking
load_dtb_addr=0x1c00000
load_initrd_addr=0x1100000
load_uimage_addr=0x800000
load_dtb=echo loading DTB $dtb_file ...; load $bootdev $device $load_dtb_addr $dtb_file
load_initrd=echo loading uInitrd ...; load $bootdev $device $load_initrd_addr /boot/uInitrd
load_uimage=echo loading uImage ...; load $bootdev $device $load_uimage_addr /boot/uImage
mainlineLinux=yes
mtdids=nand0=orion_nand
partition=nand0,2
scan_disk=echo running scan_disk ...; scan_done=0; setenv scan_usb "usb start";  setenv scan_ide "ide reset";  setenv scan_mmc "mmc rescan"; for dev in $devices; do if test $scan_done -eq 0; then echo Scan device $dev; run scan_$dev; for disknum in $disks; do if test $scan_done -eq 0; then echo device $dev $disknum:1; if load $dev $disknum:1 $load_uimage_addr /boot/uImage 1; then scan_done=1; echo Found bootable drive on $dev $disknum; setenv device $disknum:1; setenv bootdev $dev; fi; fi; done; fi; done
set_bootargs=setenv bootargs console=ttyS0,115200 root=LABEL=rootfs rootdelay=10 $mtdparts $custom_params
start_netconsole=setenv ncip $serverip; setenv bootdelay 10; setenv stdin nc; setenv stdout nc; setenv stderr nc; version;
stderr=serial
stdin=serial
stdout=serial
uenv_addr=0x810000
uenv_import=echo importing envs ...; env import -t $uenv_addr $filesize
uenv_init_devices=setenv init_usb "usb start";  setenv init_ide "ide reset";  setenv init_mmc "mmc rescan"; for devtype in $devices; do run init_$devtype; done;
uenv_load=run uenv_init_devices; setenv uenv_loaded 0; for devtype in $devices;  do for disknum in 0; do run uenv_read_disk; done; done;
uenv_read_disk=if test $devtype -eq mmc; then if $devtype part; then run uenv_read;  fi; else if $devtype part $disknum; then run uenv_read; fi;  fi
uenv_read=echo loading envs from $devtype $disknum ...; if load $devtype $disknum:1 $uenv_addr /boot/uEnv.txt; then setenv uenv_loaded 1; fi
usb_ready_retry=15
arcNumber=3338
mtdparts=mtdparts=orion_nand:1M(u-boot),4M(uImage),32M(rootfs),-(data)
ethaddr=00:10:75:2e:ae:0f
dtb_file=/boot/dts/kirkwood-goflexhome.dtb
preboot_nc=setenv nc_ready 0; for pingstat in 1 2 3 4 5; do; sleep 1; if run if_netconsole; then setenv nc_ready 1; fi; done; if test $nc_ready -eq 1; then run start_netconsole; fi
preboot=run preboot_nc
ipaddr=192.168.1.22
serverip=192.168.1.43