Sound bar turns off every 25 minutes but why?

I got a lg sound bar, lg TV and oppo 103 blu ray player. When I hook the sound bar up to the optical on TV it works fine but when I hook sound bar up to the optical on the blu ray player it turns it self off every 25 minutes. Same content being watched both ways, same settings only difference is where optical cable is plugged in. Any one know why my sound bar cuts out every 25 minutes one way but works fine another way.