The Ethernet port on the TV supports 100 Mbps, not 1 Gbps.
Try WiFi if you’ve a strong 5 GHz signal at the TV location. 2.4 GHz WiFi will not be fast enough.
If the WiFi coverage in that area is insufficient, you could add an access point, mesh node, etc and use the Ethernet cable to connect it to your home network. If you do this, make sure the new device supports 802.11ac, aka WiFi 5 (I’ve a B7 OLED, it supports WiFi 5, your LG most likely does as well).
You might also try a USB3 to Gigabit Ethernet adapter, connected to the USB3 port on your TV. See this thread:
