How to connect a non-rooted Android phone to an ethernet LAN as a client

How can I connect a non-rooted Android phone to an Ethernet LAN as a client and use it as a host? I got a public static IP. It's in my optical fiber router and I can assign it to a LAN host of my choice. Before answering, please read the following points: 1. I don't want to use the WiFi interface 2. I tried an USB-to-ethternet cable but that allows me to configure the phone as an Ethernet-to-LTE access point for the LAN attached hosts. It's a tethering service **I want to use my phone as a power-frugal server with a public static IP address.** Ciao