splitdns323fw: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/splitdns323fw - from package: dns323-firmware-tools

You may install the required package with command apt-get install {package}
Error in other languages:
splitdns323fw: bevel nie gevind nie
splitdns323fw: comandă negăsită
splitdns323fw: comando não encontrado
splitdns323fw: commande introuvable
splitdns323fw: command not found
splitdns323fw: käsku ei ole
splitdns323fw: không tìm thấy lệnh
splitdns323fw: komanda nerasta
splitdns323fw: Kommando nicht gefunden.
splitdns323fw: kommandot finns inte
splitdns323fw: komut yok
splitdns323fw: nie znaleziono polecenia
splitdns323fw: níor aimsíodh an t-ordú
splitdns323fw: no se encontró la orden
splitdns323fw: no s'ha trobat l'ordre
splitdns323fw: opdracht niet gevonden
splitdns323fw: parancs nem található
splitdns323fw: perintah tidak ditemukan
splitdns323fw: príkaz nenájdený
splitdns323fw: příkaz nenalezen
splitdns323fw: команда не найдена
splitdns323fw: командата не е открита
splitdns323fw: 命令找不到
splitdns323fw: コマンドが見つかりません