Websites can respond to both HTTPS and HTTP without issue. Over HTTP, the information you send and receive is human-readable if anybody is intercepting the communication. Also, HTTPS certificates allows to verify the ownership of that website to a certain extent (or at least that the website that you’re reaching is not being spoofed)

Do you receive an IP address from the router when you connect through ethernet ? You can tell on Windows by entering the command “ipconfig /all” in CMD and by looking at the information under your ethernet card.

It would typically be in the 10.x.x.x range, 172.16.x.x range or 192.168.x.x range. Feel free to publish the output here