We have 6 projectors installed within the 'heart of the school' they have been an absoloute nightmare turning on and off so we installed a peice of offical software from the suppliers of the projector (which is NEC) called 'PC Control Utility Pro 4'. Everything worked fine for around 6 month, I could turn all projectors on and off whenever i wanted smoothly. All projectors are connected via ethernet cable from the main PC into a router with 6 ethernets going out to each projector i have looked at the router everything is flashing green i have also tried resetting the router to no avail. Each projector has been pinged and was looking fine as I received all packets.
The software just shows a yellow triangle with an exclamation mark in it saying it cannot connect.

Does anyone have any idea's what else I could try to troubleshoot it?