Plex doesn't work properly on LG NetCast OS



Hi All
I have installed PLEX media server 3.27.1 on my PC (Win7) and I use it to watch movies on a LG Smart TV, with NetCast OS, where I have installed also the PLEX client. I have been using Plex media server for a couple of years and have been delighted. From a while, the client loads very very slow on my TV and gives me an error message like Plex is unable to connect due to an error and I need to reset PLEX or somethig like that. However, sometimes it loads my Home page, but when I try to browse the movies (click on Movies), I have to wait a lot of time to display something on that f...g black screen. Excuse me, please, my language.
Do you think it's a TV issue?, or it's a problem with NetCast's PLEX client? ...any suggestions?

Thank you very much!