This method was tested on Debian 12. Although the config file might be in a different location, it may work on any other distribution that has Systemd as their init-system.

First, we have to find out the interface name.

# ip -c link show
    

The Output should look something like this:

1: lo: LOOPBACK,UP,LOWER_UP mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens192: BROADCAST,MULTICAST,UP,LOWER_UP mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 00:0c:29:0d:d5:a2 brd ff:ff:ff:ff:ff:ff
    altname enp11s0

The device we want to edit the config for is named "ens192" in this example. Now we can go ahead and make some changes to the config file using a text editor like e.g. nano. In Debian, the config file's path is "/etc/network/interfaces"

The content of the file should look something like this:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
#allow-hotplug ens192
#iface ens192 inet dhcp
auto ens192
iface ens192 inet static
address YOUR_STATIC_IP
netmask YOUR_NETMASK
gateway YOUR_GATEWAY
dns-nameservers DNS_YOU_WANT_TO_USE

As you can see, we commented out the line containing things like "dhcp" and "allow-hotplug", and then added our own configuration. The only thing left to do now, is restarting the networking systemd service:

# systemctl restart networking
    

Congratulations! Your server has now a static local IP-Address. To double-check whether it has worked, you can look up your IP with:

# ip a