A wireless system includes a plurality of wireless nodes structured to participate in a system test of the wireless nodes. The system test includes a plurality of test packets. A packet sniffer node includes a wireless receiver, a memory storing a schedule defining transmission and reception of the test packets by the wireless nodes, and a processor cooperating with the wireless receiver and the memory to receive at least some of the test packets responsive to the schedule, and to output data corresponding to the received test packets of the system test. A monitoring computer receives the output data from the processor of the packet sniffer node. Operation of the packet sniffer node, which does not transmit, does interfere with or alter execution of the system test.