League of Legends connection issue

Hello,
I've been unable to play League of Legends for a few months now.
Every time I try to start a game, after the champion selection, a black screen appears and a few seconds later a message also appears: "Unable to connect to the server. Please check your connection status, then try to reconnect to your game."
I've tried a lot of things, uninstalling the launcher multiple times, cleaning my PC, I also tried to see if it was a firewall blocking the game, but apparently not..
So I would like to know if anyone has any idea what’s going on or if someone has already dealt with this problem and how they resolved it!
Thank you