So I have a KD-55X8500C and 500Mbps internet plan but when connected via wifi, the speed just won't go over 30Mbps no matter what. 280 is the best I get. When I connect it via a Lan cable, the speed is even worse, for some reason it won't cross 100Mbps. I was advised to use a cat6 cable but even then the speed is below 100Mbps. Idk what to do.
Use the 5GHz band and make sure mode is on ac. Also, change the wifi channel in your router settings, use an app such as wifi analyzer on your phone to find the best channel available and set your router to that.