Hi, just wanted to post it here in case someone encounters the same issue and ends up here through Google in the future.

I bought Sony Bravia A84J 65" and installed Kodi app on it with intention of watching movies from my NAS over network. The TV is connected directly to my Gigabit switch, Cisco 3560CX.

First thing that surprised me was that a £1900 TV comes with just Fast Ethernet (100Mb) network card. At first I thought it won't be a problem and while playing 1080p files (average 20GB per film) from NAS was indeed not a problem, playback of 4k UHD Blu-ray files (average 60-70GB) has proved challenging. The video would play for a minute or two fine and then would stop to buffer for few seconds.

Looking at my SNMP monitor I realised kodi generates traffic spikes when buffering videos. Most of the time it stays under 100Mb limit of the TV's network card, but from time to time it hits the ceiling and that's when the buffering was happening.

The solution has turned out to be simple. I connected USB 3.0 to Gigabit network adapter I had laying around and it just worked. No configuration required. Running a network speedtest I now reach 210Mb/s, probably limited by TV's CPU, but that's double of what built-in NIC (network interface card) achieves. More importantly, the random buffering problem is no more.