Trivumvirate

Hi guys, since a couple of days, my Download speed keeps crashing to zero every couple of minutes and at times remains 0 for a long time, see screenshot. I cannot explain why, I haven't changed any settings in uTorrent or with my router or connection. Also, it doesn't depend on the torrents I'm leeching (there's enough seeds) and as you can see, Upload speed is hardly affected. Basically I can't download anything anymore. Has anyone had the same or knows a solution? It would be much appreciated. Thanks in advance!