Here’s a quick schematic project I built for the UAS design team. They needed a 24V Power over Ethernet injector for a mission-critical antenna. My solution was to utilize the WEBENCH tool from Texas Instruments to help design a low-noise, buck-boost converter in-between two RJ45 ports. That way, one end of their system could be powered by whatever voltage it wants, while the other end (antenna) is receiving a stable 24V on the input.
In addition, I also used reference designs to help place a collection of TVS diodes to help protect against transients.
While this project never got built due to lack of need, I still learned a little bit about POE and it’s technical requirements. See the project files here: https://github.com/Arrakark/LiPoPOE