Can the router RUTX09 be powered with PoE, or is the power supply mandatory?
The router can be powered via its 1st LAN port through passive PoE. You can read about it on our Teltonika Wiki article for powering options: https://wiki.teltonika.lt/view/RUTX09_Powering_Options
Keep in mind that the powering pins might be different when it comes to choosing a PoE adapter. If a wrong adapter is chosen, the router might get damaged.