ISP

vi /etc/dhcp/dhcpd.conf

### vi ###
subnet 3.3.3.0 netmask 255.255.255.0 {
	range 3.3.3.100 3.3.3.200;
	option routers 3.3.3.254;
	option domain-name-servers 3.3.3.1;
}
### vi ###

vi /etc/default/isc-dhcp-server

### vi ###
INTERFACESv4="ens37"
### vi ###

systemctl enable --now isc-dhcp-server
systemctl restart isc-dhcp-server
systemctl status isc-dhcp-server

RT2

vi /etc/dhcp/dhcpd.conf

### vi ###
subnet 192.168.1.0 netmask 255.255.255.0 {
	range 192.168.1.100 192.168.1.200;
	option routers 192.168.1.254;
	option domain-name-servers 192.168.0.1;
}
### vi ###

vi /etc/default/isc-dhcp-server

### vi ###
INTERFACESv4="ens36"
### vi ###

systemctl enable --now isc-dhcp-server
systemctl restart isc-dhcp-server
systemctl status isc-dhcp-server