This is what happens when I try to restart networking:
root@proxmox:~# cat /etc/network/interfaces
auto lo
iface lo inet loopback
auto ens192
iface ens192 inet static
address 172.19.19.185
netmask 255.255.255.0
gateway 172.19.19.1
auto ens224
iface ens224 inet static
address 172.28.116.15
netmask 255.255.255.0
gateway 172.28.116.1
root@proxmox:~# service networking restart
Job for networking.service failed because the control process exited with error code.
See "systemctl status networking.service" and "journalctl -xe" for details.
root@proxmox:~# systemctl status networking.service
● networking.service - Raise network interfaces
Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Wed 2019-11-20 16:27:38 CET; 10s ago
Docs: man:interfaces(5)
Process: 1451 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=1/FAILURE)
Main PID: 1451 (code=exited, status=1/FAILURE)
Nov 20 16:27:38 proxmox systemd[1]: Starting Raise network interfaces...
Nov 20 16:27:38 proxmox ifup[1451]: RTNETLINK answers: File exists
Nov 20 16:27:38 proxmox ifup[1451]: ifup: failed to bring up ens224
Nov 20 16:27:38 proxmox systemd[1]: networking.service: Main process exited, code=exited, status=1/FAILURE
Nov 20 16:27:38 proxmox systemd[1]: networking.service: Failed with result 'exit-code'.
Nov 20 16:27:38 proxmox systemd[1]: Failed to start Raise network interfaces.
root@proxmox:~#