https://www.paessler.com/Download_PRTG/PRTG_Freeware
SponsoredMonitor your entire network - LANs, VM, servers, applications, etc. - easily with PRTG. Assure network performance & availability. PRTG uses SNMP, WMI, Packet Sniffing, NetFlow.
Types: PRTG Network Monitor, PRTG Enterprise Monitor, PRTG Hosted Monitor