Hi, welcome here
SME server (as Nethserver, that you already know) relies on db/templates/fragments/event paradigm, so editing conf file is the wrong approach to the problem (and you've been already told so elsewhere)
if you need to change your dhcp range,
config setprop dhcpd start your_first_ip end your_last_ip
expand-template /etc/dhcpd.conf
service dhcpd restart
moreover, please take some time to read the documentation, thank you