Today I rebooted my ZS router, during an attempt to install an FXO card for the asterisk (eventually there were no pci slots free so it was not installed).
Upon the boot the ZS did not behave normally. Lots of files seemed to be missing, such as modprobe, iptables and agetty. The box booted, but it was completely unusable. I didn’t have tty to see what is wrong. I booted from another CD to fsck the partitions, but nothing changed. To make long story short I ended up restoring a backup 4 months old, cause the other 2 were having the same problem. Important files are missing and the router cannot boot correctly. For the time being I have no time to investigate it, but if any developer would like to take a look on that I could upload the backup on the internet.