Even if you stick with 21.0.x, you must maintain it properly. Here’s a checklist used by MSPs:
While the classic web interface remains available, the 21.0.x cycle brought significant performance improvements to the PRTG Desktop application. Built on cross-platform frameworks, PRTG Desktop allows administrators to manage multiple core servers simultaneously from a single, unified interface, streamlining operations for Managed Service Providers (MSPs). Native Cloud and Virtualization Sensors prtg network monitor 21.0.x
Additionally, the gained support for Python 3.9+ (older versions were Python 2.7 only). Even if you stick with 21
Sensors are the heart of PRTG. Version 21.0.x introduced several new sensor types and improved existing ones: Native Cloud and Virtualization Sensors Additionally
Note: For installations running over 10,000 sensors, Paessler recommends distributing the load across multiple core instances or deploying extensive Remote Probes. Step-by-Step Configuration Strategy
Ensure scripts return data in the standard PRTG XML or JSON format.
Regular updates within the 21.x branch ensured better security protocols to protect sensitive monitoring data.