networking.service status failed after install ifupdown2

[jaceqp]

Hi there.
I installed remotely ifupdown2 on my PVE 7 using SSH console (putty). I believe ifupdown2 install process seem to remove ifupdown. I did NOT perform update ifupdown packages prior to ifupdown2 installation (not a recommended move as I read after that). During installation I got dc from Proxmox (but perhapse not uncommon).
Yet after a while I still couldn't getback to proxmox. Lucky for me I was able to access server via remote management console. So after a networking service restart I could access Proxmox from network again.
Then I tried to do some light network changes from GUI, yet had an error (as I recall) saying that ifupdown2 is in incompatible edition.
So I installed 'old' ifupdown and after that that's what I see in my networking.service status:

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 2021-09-15 20:53:42 CEST; 12h ago
       Docs: man:interfaces(5)
    Process: 450844 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=1/FAILURE)
   Main PID: 450844 (code=exited, status=1/FAILURE)
        CPU: 114ms

Sep 15 20:53:42 ****proxmox systemd[1]: Starting Raise network interfaces...
Sep 15 20:53:42 ****proxmox ifup[450871]: RTNETLINK answers: File exists
Sep 15 20:53:42 ****proxmox ifup[450844]: ifup: failed to bring up vmbr0
Sep 15 20:53:42 ****proxmox systemd[1]: networking.service: Main process exited, code=exited, status=1/FAILURE
Sep 15 20:53:42 ****proxmox systemd[1]: networking.service: Failed with result 'exit-code'.
Sep 15 20:53:42 ****proxmox systemd[1]: Failed to start Raise network interfaces.

I'm also unable to perform:

service restart networking.service

My main interface is vmbr0, however I have 8 NICs in total... No vlans, bonding etc. One of nic's is in a pci passthrough state to one of my VM's.

01:00.3 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01)


etc/network/interfaces:

auto lo
iface lo inet loopback

iface eno1 inet manual

iface eno2 inet manual

iface eno3 inet manual

iface eno4 inet manual

iface enp5s0f0 inet manual

iface enp5s0f1 inet manual

iface enp6s0f0 inet manual

iface enp6s0f1 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.1.238/24
        gateway 192.168.1.252
        bridge-ports eno1
        bridge-stp off
        bridge-fd 0

auto vmbr21
iface vmbr21 inet manual
        bridge-ports enp5s0f0
        bridge-stp off
        bridge-fd 0

auto vmbr22
iface vmbr22 inet manual
        bridge-ports enp5s0f1
        bridge-stp off
        bridge-fd 0

Here's some apt logs:

/var/log/apt/history.log.1.gz                                                                                                                                                                                      340/340               100%

Start-Date: 2021-09-15  20:16:47
Commandline: apt install ifupdown2 -y
Install: ifupdown2:amd64 (3.0.0-1)
Remove: ifupdown:amd64 (0.8.36)
End-Date: 2021-09-15  20:16:53

Start-Date: 2021-09-15  20:47:17
Commandline: apt-get install ifupdown
Install: ifupdown:amd64 (0.8.36)
Remove: ifupdown2:amd64 (3.0.0-1)
End-Date: 2021-09-15  20:47:21

/var/log/apt/term.log.1.gz                                                                                                                                                                                        1933/3582               53%

Log started: 2021-09-15  20:16:47
.[1mdpkg:.[0m ifupdown: dependency problems, but removing anyway as you requested:
 ifenslave depends on ifupdown.

(Reading database ...
(Reading database ... 5%
(Reading database ... 10%
(Reading database ... 15%
(Reading database ... 20%
(Reading database ... 25%
(Reading database ... 30%
(Reading database ... 35%
(Reading database ... 40%
(Reading database ... 45%
(Reading database ... 50%
(Reading database ... 55%
(Reading database ... 60%
(Reading database ... 65%
(Reading database ... 70%
(Reading database ... 75%
(Reading database ... 80%
(Reading database ... 85%
(Reading database ... 90%
(Reading database ... 95%
(Reading database ... 100%
(Reading database ... 58377 files and directories currently installed.)
Removing ifupdown (0.8.36) ...
Selecting previously unselected package ifupdown2.
(Reading database ...
(Reading database ... 5%
(Reading database ... 10%
(Reading database ... 15%
(Reading database ... 20%
(Reading database ... 25%
(Reading database ... 30%
(Reading database ... 35%
(Reading database ... 40%
(Reading database ... 45%
(Reading database ... 50%
(Reading database ... 55%
(Reading database ... 60%
(Reading database ... 65%
(Reading database ... 70%
(Reading database ... 75%
(Reading database ... 80%
(Reading database ... 85%
(Reading database ... 90%
(Reading database ... 95%
(Reading database ... 100%
(Reading database ... 58341 files and directories currently installed.)
Preparing to unpack .../ifupdown2_3.0.0-1_all.deb ...
Unpacking ifupdown2 (3.0.0-1) ...
Setting up ifupdown2 (3.0.0-1) ...
Installing new version of config file /etc/default/networking ...
Processing triggers for man-db (2.9.4-2) ...
Log ended: 2021-09-15  20:16:53

Log started: 2021-09-15  20:47:17
dpkg: ifupdown2: dependency problems, but removing anyway as you requested:
 ifenslave depends on ifupdown; however:
  Package ifupdown is not installed.
 1Help                  2UnWrap                3Quit                   4Hex                    5Goto                   6                      7Search                 8Raw                    9Format                10Quit

Anyway for now all my VM's are running, including network services. Not sure how PM would behave during/after a full reboot - not trying to do it yet...
I wonder if I got some damaged package dependencies etc. Any ideas to fix networking on that?