# How vagrant-libvirt Plugin Deals with Duplicate Subnets

DevFeed: [How vagrant-libvirt Plugin Deals with Duplicate Subnets](<https://devfeed.tech/articles/how-vagrant-libvirt-plugin-deals-with-duplicate-subnets-26994.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2026/09/vagrant-libvirt-duplicate-subnets/>)

Published: 2026-09-16T06:27:00Z

Content type: tutorial

Language: en

Sources: [ipSpace.net blog](<https://devfeed.tech/sources/ipspace-net-blog.md>)

Topics: [Vagrant](<https://devfeed.tech/topics/vagrant.md>), [virtual machines](<https://devfeed.tech/topics/virtual-machines.md>), [Linux](<https://devfeed.tech/topics/linux.md>), [Ubuntu](<https://devfeed.tech/topics/ubuntu.md>)

Tags: [debugging](<https://devfeed.tech/tags/debugging.md>), [linux](<https://devfeed.tech/tags/linux.md>), [vagrant](<https://devfeed.tech/tags/vagrant.md>), [virtual-machines](<https://devfeed.tech/tags/virtual-machines.md>), [virtualization](<https://devfeed.tech/tags/virtualization.md>)

## AI overview

The article explains that vagrant-libvirt can fail when an existing libvirt virtual network has the same IP subnet as the desired management network but a different name. It identifies the resulting network-name mismatch and reports that correcting the network definition in the Vagrantfile resolves the problem.

## Source excerpt

TL&DR: Badly. The vagrant-libvirt plugin mysteriously crashes when an existing virtual network (with a different libvirt name) uses the same IP subnet as the desired management network. Background: netlab is using the vagrant-libvirt plugin to manage libvirt/KVM virtual machines with Vagrant. As I already have that infrastructure, I use it to start standalone virtual machines (usually to test various Ubuntu releases) on my Linux server. Things work great... until they don't. Here's how I managed to waste half a day chasing imaginary gremlins caused by a simple error. Read more ...