Target machine actively refused connection

When attempting to connect to some of my field PMUs (SEL 734) I am receiving the following error from PMU Connection Tester.

"No connection could be made because the target machine actively refused it

1 connection attempted"

I believe this would generally indicate something is incorrect in the IP/Device ID/Etc. I’ve give it. Is there a way to further test what exactly is incorrect? Thanks!


The most explicit explanation of this error would be the PMU Connection Tester sent a SYN packet to initiate the TCP connection and received an RST packet in response. The simplest explanation would be that the remote system that the PMU Connection Tester is connecting to is not listening on the endpoint (IP address + port) that the PMU Connection Tester attempted to use to communicate with the device. This error may indicate one or more of the following:

  • You entered the IP address and/or port wrong.
  • Your network is routing your packets to the wrong system.
  • The software on the remote device is not operating.
  • There is an IP version mismatch (device is listening on IPv4 but PMU Connection Tester is attempting connection over IPv6 or vice versa).