I am looking at different power-line adapters (that transmit Ethernet signal over the normal electric network in the house) and I am considering to plug a PoE switch to one of these. How can I figure out if the adapter supports PoE?
Any of these Powerline will support this as it is the switch with PoE that provides the actual power to the device(s). The Powerline ethernet devices simply replace a run of cable or a WiFi connection.
You simply connect ethernet at each end and then connect your PoE switch.
I use several different Powerline Ethernet devices and have not seen any that also provide PoE. However, I am sure someone will add the information if such exist.