We started early this year using the WS-12-250-AC for powering radar units (simple PoE solution) and have had zero issues with them.
However, when a customer of ours reported that they did not get any connection to the unit from a pc but the Netonix interface said it was connected we felt something was up.
We could ping the unit from the switch itself but not from a connected laptop. The connected radar unit looked like it should in the interface (watts use etc).
Upgrading to 1.5.6 resolved the issue and we are doing it on the remaining switches.
Thank you for posting this thread. Otherwise we would have been hairless by now.

Best Regards