I have an OLED77C3PUA. Two days ago, I was watching a video on a Roku Ultra that is connected to my TV when two popup messages appeared the first said "wired network is disconnected" the second appeared about 10 seconds later saying "wired network is connected". The cycle of messages never stops.
I tried unplugging the TV and holding the power button ON for 20 seconds. Powered the router of and back on and followed up with powering the TV back on. This didn't solve the problem,
I updated the apps and reset the TV to factory default settings; still did not fix the problem.
I swapped ports on the router and replaced the ethernet cable. Still no luck.
The TV works without problems when connected to the network with WIFI. Also, the Roku is connected to the same router and it has no connectivlity problems.
When I disconnect the ethernet cable from the TV there is a message "wired network cable is disconnected" The router port LEDs indicate activity on the port used by the TV. This indicates to me that there is communication between the TV and the router so I don't think the problem is cable or hardware related.
I called LG tech support. They said that a tech could come out to repair the TV. That would likely be a very expensive service call because the nearest tech is about an hour and a half away. If it is a hardware problem, parts would need to ordered and they would either take the TV or return with parts so it is likely the tech would have to make two trips. I suspect the problem is caused by software related to DNS or something else associated with IP protocol handling. It seems unlikely that the tech will be able to resolve this kind of problem.
For now I will leave the ethernet cable disconnected to get rid of the popups and connect the TV to the network via WIFI.
Nothing changed about the network wiring or network architecture prior to the appearance of the problem so I am wondering if an OS update caused the problem. LG tech support wasn't any help.