Vendor lock-in and proprietary file formats are the bane of the software world. The lack of a drop-in free/libre Visio replacement to draw network diagrams has long puzzled me. What do free/libre IT professionals use to diagram networks?
The attractions of Visio are stencils, connectors, and snap points.
Searching the web finds many discussions about Visio alternatives. Review writers post the usual click-bait puffery and focus only on flow diagrams and not network diagrams.
libvisio? A support library. Some command line conversion tools. Not designed to draw from scratch.
Dia? No comprehensive network stencils. Not maintained anymore. Coyote ugly.
Pencil? A wireframing and sketching tool. No network stencils.
Calligra Flow (formerly Kivio)? No meaningful network stencils. The usual KDE package bloat, er, overhead to use one app.
Graphviz? Classic geek poop.
yEd? Java. Closed source.
Online (SaaS) tools? Closed source. Privacy and data mining issues.
Inkscape? A well-liked vector drawing tool, but not a drag-and-drop stencil tool. No native network stencils. Inkscape supports SVG and connectors.
LibreOffice Draw? Similar to Inkscape. No native network stencils. Draw supports SVG and connectors.
Possible work-arounds that require sweat equity:
Creative Commons third party images. Available in Fedora as a package. Not available as a package in other distros, including CentOS, which targets, um, enterprise users.
Of these options, Inkscape and Draw seem inviting for non artists as long as some stencil shapes are pre-installed.
The Network Diagram 101 site provides some nice advice for anybody interested in network diagramming. I would like to read some good tutorials based on that web site but using free/libre tools.
In the end, drawing network diagrams with free/libre software is a challenge.