I'm going to read the two manuals at https://www.lg.com/us/support/product/lg-BP175.DUSALLG
Page 16 seems to start to document how to setup the Ethernet and it tells us to use manual settings if the DHCP fails. DHCP usually works but with your router you could have MAC filtering or a firewall enabled. I can't tell you about this as you have to check your setup.
Hi, I bought an LG BP175 today and connected the Ethernet cable to my Apple AirPort Extreme Router, but when I tried to configure it, it wouldn’t connect and said to check LAN cable. I reset both the cable modem and router, turned DVD player off and on, and still no connection. To prove that the cable and connectivity to my router was not the cause, I took the ethernet cable from my LG TV (which I know works) and plugged it into the DVD player. Still nothing. Is there a reason why it can’t automatically connect in a similar fashion to my TV or do I need to do a manual setup? Thanks in advance, Bonnie