root@ns3001958:~# /etc/init.d/networking restart
[....] Restarting networking (via systemctl): networking.serviceJob for networki                                                                                                                     ng.service failed because the control process exited with error code.
See "systemctl status networking.service" and "journalctl -xe" for details.
 failed!
root@ns3001958:~# 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 Sun 2019-10-27 20:55:14 UTC; 6s ago
     Docs: man:interfaces(5)
  Process: 3276 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=1/FAILURE)
  Process: 3265 ExecStartPre=/bin/sh -c [ "$CONFIGURE_INTERFACES" != "no" ] && [ -n "$(ifquery --read-environment --list --exclude=lo)" ] && udevadm settle (code=exited, status=0/SUCCESS)
 Main PID: 3276 (code=exited, status=1/FAILURE)
      CPU: 88ms

Oct 27 20:55:14 ns3001958 systemd[1]: Starting Raise network interfaces...
Oct 27 20:55:14 ns3001958 ifup[3276]: Waiting for vmbr0 to get ready (MAXWAIT is 2 seconds).
Oct 27 20:55:14 ns3001958 ifup[3276]: RTNETLINK answers: File exists
Oct 27 20:55:14 ns3001958 ifup[3276]: ifup: failed to bring up vmbr0
Oct 27 20:55:14 ns3001958 systemd[1]: networking.service: Main process exited, code=exited, status=1/FAILURE
Oct 27 20:55:14 ns3001958 systemd[1]: Failed to start Raise network interfaces.
Oct 27 20:55:14 ns3001958 systemd[1]: networking.service: Unit entered failed state.
Oct 27 20:55:14 ns3001958 systemd[1]: networking.service: Failed with result 'exit-code'.

root@ns3001958:~# ping ya.ru
PING ya.ru(ya.ru (2a02:6b8::2:242)) 56 data bytes
64 bytes from ya.ru (2a02:6b8::2:242): icmp_seq=1 ttl=50 time=58.3 ms
64 bytes from ya.ru (2a02:6b8::2:242): icmp_seq=2 ttl=50 time=55.8 ms
64 bytes from ya.ru (2a02:6b8::2:242): icmp_seq=3 ttl=50 time=55.8 ms
^C
--- ya.ru ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 55.868/56.690/58.334/1.178 ms
root@ns3001958:~# ip link
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: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbr                                                                                              0 state UP mode DEFAULT group default qlen 1000
    link/ether 70:54:d2:19:9e:10 brd ff:ff:ff:ff:ff:ff
3: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode                                                                                               DEFAULT group default qlen 1000
    link/ether 70:54:d2:19:9e:10 brd ff:ff:ff:ff:ff:ff
root@ns3001958:~# ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group defaul                                                                                              t qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbr                                                                                              0 state UP group default qlen 1000
    link/ether 70:54:d2:19:9e:10 brd ff:ff:ff:ff:ff:ff
3: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP grou                                                                                              p default qlen 1000
    link/ether 70:54:d2:19:9e:10 brd ff:ff:ff:ff:ff:ff
    inet 37.59.50.152/24 brd 37.59.50.255 scope global vmbr0
       valid_lft forever preferred_lft forever
    inet6 2001:41d0:8:6d98::1/128 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::7254:d2ff:fe19:9e10/64 scope link
       valid_lft forever preferred_lft forever
root@ns3001958:~# cat /etc/net
netconfig  network/   networks
root@ns3001958:~# cat /etc/network/
if-down.d/            if-up.d/              .pve-interfaces.lock
if-post-down.d/       interfaces
if-pre-up.d/          interfaces.d/
root@ns3001958:~# cat /etc/network/interfaces
# network interface settings; autogenerated
# Please do NOT modify this file directly, unless you know what
# you're doing.
#
# If you want to manage parts of the network configuration manually,
# please utilize the 'source' or 'source-directory' directives to do
# so.
# PVE will preserve these directives, but will NOT read its network
# configuration from sourced files, so do not attempt to move any of
# the PVE managed interfaces into external files!

auto lo
iface lo inet loopback

auto eno1
iface eno1 inet manual

auto vmbr0
iface vmbr0 inet static
        address  37.59.50.152
        netmask  24
        gateway  37.59.50.254
        bridge-ports eno1
        bridge-stp off
        bridge-fd 0

root@ns3001958:~# /etc/init.d/networking restart
[....] Restarting networking (via systemctl): networking.serviceJob for networki                                                                                              ng.service failed because the control process exited with error code.
See "systemctl status networking.service" and "journalctl -xe" for details.
 failed!
root@ns3001958:~# systemctl status networking.service
● networking.service - Raise network interfaces
   Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor prese
   Active: failed (Result: exit-code) since Thu 2019-10-24 13:38:36 UTC; 13s ago
     Docs: man:interfaces(5)
  Process: 4916 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=
  Process: 4903 ExecStartPre=/bin/sh -c [ "$CONFIGURE_INTERFACES" != "no" ] && [
 Main PID: 4916 (code=exited, status=1/FAILURE)
      CPU: 88ms

Oct 24 13:38:36 ns3001958 systemd[1]: Starting Raise network interfaces...
Oct 24 13:38:36 ns3001958 ifup[4916]: Waiting for vmbr0 to get ready (MAXWAIT is
Oct 24 13:38:36 ns3001958 ifup[4916]: RTNETLINK answers: File exists
Oct 24 13:38:36 ns3001958 ifup[4916]: ifup: failed to bring up vmbr0
Oct 24 13:38:36 ns3001958 systemd[1]: networking.service: Main process exited, c
Oct 24 13:38:36 ns3001958 systemd[1]: Failed to start Raise network interfaces.
Oct 24 13:38:36 ns3001958 systemd[1]: networking.service: Unit entered failed st
Oct 24 13:38:36 ns3001958 systemd[1]: networking.service: Failed with result 'ex
root@ns3001958:~#