Prtg Network Monitor 21.0.x Access

Paessler officially ended full support for 21.0.x in mid-2023 (standard support lasts ~24–30 months per major version). That means:

Recommendation: If your 21.0.x instance is internet-facing, place it behind a reverse proxy (nginx, IIS ARR) with modern WAF rules, or migrate to a supported version.

Remote probes frequently disconnect.

Why did the 21.0.x release resonate so deeply with the SysAdmin community? It was a feature-rich, stability-focused update. prtg network monitor 21.0.x

PRTG 21.0.x supports over 200 sensor types. Notable additions/changes:

Given its age (released 2021), you must harden 21.0.x for modern threats.

PRTG Network Monitor 21.0.x represents a significant milestone in the Paessler AG monitoring roadmap. This release cycle focused heavily on modernizing the user interface, improving security protocols, and introducing architecture changes to prepare the software for future updates (such as the transition to PRTG 23). Paessler officially ended full support for 21

While the 21.x branch is now considered a "Previous Version," it remains widely deployed in legacy environments for its stability and specific feature set.

If you already run IIS (Internet Information Services) on port 80/443, PRTG’s web server fails.

Note: As of 2025, direct downloads from Paessler for 21.0.x may be archived. You typically need an active maintenance contract to access older versions. Recommendation : If your 21

Minimum Requirements:

Installation Steps (Typical for 21.0.x):