Its very rare, but sometimes I also get the "Disconnection" sign in the bottom of the screen while I'm playing.
Have you tried using a cable?
Are you playing on EU Servers when you're actually USE/W?
Are you using some kind of a boxer? (Internet / TV at the same time, on the same internet) Try to disconnect your TV while playing.
Have you re-installed HoN after the patch?
~Regards, Markus.