I was running RC4 on MR2 and Barnacle was a little sketchy to manage. Worked sometimes, then not others. It particularly didn't like the Y5 app I use to dynamically switch wifi networking. The stock wifi hotspot app was not bothered by Y5 strangely. So, if i turned it off (and then wifi off) before turning on Barnacle, chances are barnacle would work.
I just bumped the radio to the new official mr2 and barnacle works a little better but that really doesn't make sense to me why. Don't know but if you are running other apps sometimes it fouls up the start up process.
Hope my experiences help.