Been having this problem for about 4 years, started to notice it on LoL when I kept getting disconnected from chat every minute or so. Last year it started getting worse, when I'm playing csgo it will cut out for about a second (will link yt clip for example). It's now got the the point where it completely kicks me off some games, TERA and Black Desert Online are the only two I know of so far, I'm not sure what it does and I've searched online for a similar problem but couldn't find much, it basically cuts my connection from the game for a split second and the game says disconnected from server about 30 seconds or more later, sometimes a few minutes. I also forgot to mention that if im in discord or teamspeak, it doesn't disconnect at all on there, only ingame. Also I'm using an ethernet cable.
https://www.youtube.com/watch?v=UPGX1UZ18IU
https://www.youtube.com/watch?v=UPGX1UZ18IU
