Eetheernet plugged into lan from router other to antenna, hard to sreew up conneection, poweer supply camee with unit. Second unit to do same. Power litee goees out soon as i connect lan to anything

When I energize the unit power light comes on, then when I hook the lan to my computer power light goes out. If fact it goes out whenever I plug the lan in. This is the second unit whith the same...