If you are currently running version 21.0.x, planning a migration to it, or trying to understand its legacy in the shadow of newer releases, this article covers everything you need to know. PRTG Network Monitor is an all-in-one infrastructure monitoring solution. The 21.0.x branch (released in early 2021) was a significant update that bridged the gap between the older 20.x series and the modern UI overhauls of later versions.
In the ever-evolving landscape of network monitoring tools, few names command as much respect as PRTG Network Monitor from Paessler AG. While the latest versions have moved past the 21.x branch, the PRTG Network Monitor 21.0.x release family represents a pivotal, mature, and highly stable era for the software. For many IT administrators, this version remains the "Gold Standard" of on-premises monitoring due to its balance of modern features, resource efficiency, and proven reliability. prtg network monitor 21.0.x
PRTG 21.0.x changes the underlying database schema. Once you upgrade, you cannot downgrade easily. You must take a full backup of the \ProgramData\Paessler\PRTG Network Monitor\ directory. If you are currently running version 21
However, for greenfield deployments in 2025, you should install the latest stable build. But for those of you maintaining legacy infrastructure, remains a reliable, trusted sentinel watching over your packets and pings. Disclaimer: Software versions move quickly. Always check Paessler’s official knowledge base for the latest support status of version 21.0.x. In the ever-evolving landscape of network monitoring tools,
It represents the last of the "truly on-premises, simple to license" versions. If you are currently running 21.0.x successfully, there is no urgent reason to leave it—provided you have layered network security controls around it.