Network error after champ select

It's every second match. I'm in a queue, then in the champ select. After that I'm having a black screen waiting for the loading screen to show up.

But then an error message appears, that says, that I'm disconnected from the servers and I should check my connection and retry it. I checked my connection and everything was fine. But I couldn't reconnect, only after 5 minutes where the match was already in progress.

I also got a 10 minutes leaver buster and then 20 minutes.

Seriously, wtf is this? I got punished for things I'm not responsible for.