But it doesn't work reliably with your supplied cable which is within your own specs. Seems mighty strange that I can buy a $20 POE injector and run it down 100 metres?
Then something else isn’t right.
For several years I’ve been using the stock cable, a 15 footer I made myself and a random 6 foot from an old router. All used extensively and in various situations.
I’ve never experienced a reliability problem.