It might not have anything to do with your situation but I have had problems with Hashfast devices disconnecting from cgminer if the internet connection is disrupted. They would try to return but on the two occasions this has happened I had to power cycle everything to get it going again.
That might very well be the case. I am using Comcast Xfinity and their service is really flaky. Sometimes the internet connection drops completely for a minute or so before resuming. On the other hand, the BJ itself does not feel really stable either. It reconnects every hour or so:
