Power over Ethernet · controlled diagnosis
Is the failure in the PSE, budget, cable, or endpoint?
Record what changes with one known-good cable, port, lower load, or compatible injector instead of replacing the whole path at once.
Observed controls
Detection and data are separate evidence
A PD can fail PoE detection while the cable still carries data, or it can receive power while the Ethernet link fails. Preserve the same endpoint and change one cable, port, or PSE at a time.