I've been getting lots of lag and disconnects too. I did some research and tons of folks are on the same boat.

It appears bli change its netcode to help on bandwidth cost. I think how it works is their now p2p . Since the patch I have notice 2 new ports that blizzards using. Both loading equal amount this is where the latency is coming from I think.

There is a lot of pist of people from this, so perhaps they made fix it soon.