After update, networking is now broken

[ajcm73]

javier@javier-H110M-S2:~$ sudo systemctl restart networking
Failed to restart networking.service: Unit networking.service not found.
javier@javier-H110M-S2:~$ sudo service network-manager restart
Failed to restart network-manager.service: Unit network-manager.service not
found.
javier@javier-H110M-S2:~$ ifdown eth0
No se ha encontrado la orden ?ifdown?, pero se puede instalar con:
sudo apt install ifupdown # version 0.8.35ubuntu2, or
sudo apt install netscript-2.4 # version 5.5.3
javier@javier-H110M-S2:~$ sudo apt install ifupdown
Leyendo lista de paquetes... Hecho
Creando ?rbol de dependencias
Leyendo la informaci?n de estado... Hecho

sudo apt install netscript-2.4
Leyendo lista de paquetes... Hecho
Creando ?rbol de dependencias

Configurando bridge-utils (1.6-3ubuntu1) ...
Configurando netscript-2.4 (5.5.3) ...
Created symlink /etc/systemd/system/multi-user.target.wants/netscript.service → /lib/systemd/system/netscript.se
rvice.
Created symlink /etc/systemd/system/network-online.target.wants/netscript.service → /lib/systemd/system/netscrip
t.service.
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
Procesando disparadores para man-db (2.9.3-2) ...
Procesando disparadores para systemd (246.6-1ubuntu1.2) ...
javier@javier-H110M-S2:~$ ifdown eth0

ifdown: you must be root to run this command.

javier@javier-H110M-S2:~$ sudo ifdown eth0
javier@javier-H110M-S2:~$ sudo systemctl restart networking
Failed to restart networking.service: Unit networking.service is masked.
javier@javier-H110M-S2:~$

[ajcm73]

This is I have maked.

[ajcm73]

Hello again:

I want to continue with this post because I think this can help to fix this problem.

After installing kubuntu and kde neon I have realized that you can have with the Grub program as long as this grub has a kernel 5.8 or higher. Internet sometimes fails, sometimes it works, I have even restarted the pc from grub starting windows 10 and it turns out that windows 10 appears without network devices and I have to restart the pc several times. I have one SSD with kubuntu and kdeneon and other ssd with windows 10. My boot list in grub is as follows:

-Kde Neon
-Windows boot.
-Kubuntu

Kde neon have 5.4.71 kernel and it is this grub but if grub is installed with kubuntu then newtwork fails.