You have disconnected. Please check your internet connection (2018)

Hi, I hope someone has the solution for this because I am about to stop playing league forever if I can't fix this. It started like two months ago and still could not find the solution. My internet connection is fine, I played a lot of games with this internet but since one update (I dont remember which one) this problem started. So, basically the problem is, after champ select I go to the loading screen then the screen goes black and after 30 seconds the sign saying "You have disconnected"

Please help! Thanks in advance