I cannot play, due to connection issues.

After the patch, i tried to play some matches, but couldn't finish anyone due to frequent reconnection events and client crashes. I checked my internet connection for days, scanned the entire pc for some problems on my side, but couldn't find anything. I can still play many games which use internet connection perfectly, without lag or issues like this. I went forward and re-installed the entire game, but that didn't fix the problem. Now as soon as i get into a match and i press ANY button, or i click to move, the champion goes slightly forward and then i get the reconnection window. I already tried pretty much everything on the support page, but it didn't fix the problem. Any ideas? I'm running on Windows 8.1 with 8.0Gb RAM and latest graphic card, so i don't think it's a hardware related issue. Thanks.