RouterBOARD hardware

QRT 5 PoE odd behavior

I have a QRT 5 that works great if I am connected directly to it. But when I try to plug it in to a Linksys, Netgear or Belkin router, it kills power to the QRT and the PoE light goes dim and starts blinking. I have tried different cables and PoE injectors and the same thing happened no matter what port I try it in. Now the most interesting thing is that it will also work fine with the PoE Injector in port 2,3 or 4 in my hAP ac light but wil not work or be powered by port 5. Any one have a clue what the problem may be?

How long is the cable run to qrt?

it doesn’t matter it could be 6" to several feet. I’ve tried several cables sitting right next to it, same result.