Repairing VM broken by my changing network configuration

English Virtualization
1

I have been tidying up my network configuration which had been misconfigured and now I cannot start my Win10 VM. Here is the error message I have:-

Error starting domain: Cannot get interface MTU on 'br0': No such device

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 72, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 108, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 57, in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/domain.py", line 1425, in startup
    self._backend.create()
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 1373, in create
    raise libvirtError('virDomainCreate() failed')
libvirt.libvirtError: Cannot get interface MTU on 'br0': No such device

I am not confident I have my network correct and this may be the problem. Here is what my connections look like:-

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 34:40:b5:93:38:d0 brd ff:ff:ff:ff:ff:ff
    altname eno1
    altname enp11s0f0
    inet 192.168.169.134/25 brd 192.168.169.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::9fef:a051:9a5c:190d/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 34:40:b5:93:38:d1 brd ff:ff:ff:ff:ff:ff
    altname eno2
    altname enp11s0f1
4: usb0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master nm-bridge state UNKNOWN group default qlen 1000
    link/ether 36:40:b5:93:38:d5 brd ff:ff:ff:ff:ff:ff
    altname enp0s26f1u2
7: nm-bridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 36:40:b5:93:38:d5 brd ff:ff:ff:ff:ff:ff
10: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 52:54:00:53:fe:60 brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever

I am not sure about the virbr0, where it came from and where it found the ip address.
Any advice gratefully received please.
Budgie2

2

See if this helps
https://www.reddit.com/r/VFIO/comments/fvg3eo/how_to_set_up_a_bridge_so_that_both_host_and/

3

Hi and thanks for the link. That gave me the info I needed to find my mistake and I have fixed the problem. No need to use nmcli which is an excellent tool but requires a good bit of knowhow. I just used nmtui as advised by Malcolm and sorted out my error. Fortunately I had another machine as an example.
Thanks again,
Budgie2

4

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