1. With TACACSGUI installation script

2. Change netplan configuration file

3. Use web interface

With TACACSGUI installation script

Login to server (default login/password is tacgui/tacgui) and execute next command:

sudo ~/tgui_install/tacacsgui.sh

Then follow the example of ip address changing:

###############################################################
##############   TACACSGUI Network Settings Script    #########
###############################################################

ver. 1.0.0

##############     List of available options    ##############

1) Show Interface List      4) Clear and Refresh Menu
2) Show Interface Settings  5) Back to Main Menu
3) Configure interface

Please enter your choice (4 to clear output): 1 #show list of interface

### Show Interface List ###

lo
ens160

Please enter your choice (4 to clear output): 2 #show interface settings

### Show Interface Settings ###

Type the name of interface: ens160 #type interface name
Netifaces info:
ip address: 10.6.20.10/24
defaultgw: 10.6.20.1
nameservers: 8.8.8.8, 77.88.8.8

Please enter your choice (4 to clear output): 3 #change interface settings


Type the name of interface: ens160 #type interface name
######################## 
Welcome to interactive mode of
Network Interface Configuration
########################

IP Address: 10.6.20.10 #type ip address
Mask: 255.255.255.0 #type mask
Network Address: 10.6.20.0/24 
Gateway (Optional): 10.6.20.1 #type gateway
Nameservers (Optional, comma separated): 8.8.8.8 #type nameservers
########################
Please check settings:
IP Address: 10.6.20.204/24
Gateway: 10.6.20.1
Nameservers: 8.8.8.8
Is it correct? (y/n): y #type y if everything correct
done
Done

Please enter your choice (4 to clear output): 5 #back to installation menu

Change netplan configuration file

More information about netplan config you can find here.

You can find configuration file in /etc/netplan/. For example, we have configuration file /etc/netplan/01-netcfg.yaml. To start edit configuration file use next command:

sudo vim /etc/netplan/01-netcfg.yaml

network:
  ethernets:
    ens160:
      addresses: [10.6.20.10/24]
      dhcp4: 'no'
      dhcp6: 'no'
      gateway4: 10.6.20.1
      nameservers:
        addresses: [8.8.8.8]
  renderer: networkd
  version: 2

To apply changes use next command:
sudo netplan apply

Use web interface

Also you can use web interface to change network settings.