Virtual NIC sometimes needs to be manually reconnected to vmbr

Chicken76

Renowned Member
Jun 26, 2017
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Environment:
  • PVE 8.4.14
  • VM with VirtIO NIC configured in a VLAN
  • some three switches away I have another device connected to a port that's native in that VLAN
  • everything worked fine for months, years, eons
Today I had to unplug that device and change it's position and arrange the cables a bit. After plugging everything back, I have no connectivity to that device.
What I did to troubleshoot:
  • check the device and everything looks to be functioning ok
  • check the cable
  • unplug and plug back in the cable
  • replace the cable
  • restart that remote switch
  • unplug from the switch and connect device directly to a laptop. Device is accessible and working properly, so it's a network issue
In the end what solved the problem was this:
  • kept a ping running to that device that was showing "Request timed out."
  • went into the VM's NIC configuration and check the "Disconnect" checkbox. Hit OK.
  • ping started showing "Destination host unreachable."
  • unchecked the Disconnect checkbox and as soon as I hit OK, I started getting replies.
Has anyone encountered this behavior?
I remeber having similar issues over the years but I didn't troubleshoot this far, I just restarted the VM and everything worked again. But it lookls like a reconnect of the vNIC to the linux bridge is all that's needed.