Mkv movie problem

Hi, I've got a 47lm660s tv and when I try to play a mkv movie, the tv displays "loading" every 3-4 seconds. I've noted this happens more frequently in the movie with high bitrate or big size. The tv and pc are wifi connected. Is it normal that when I connected my pc to, the same router, with an ethernet cable, I can't see serviio server on the tv?
Can you solved my problems? Thanks to all.

I have an LG tv although not the same as yours, and it does not natively support .mkv files?

Have you checked if yours does?