We have had a Series 4100 HP printer for 1 year. When trying to print with it, we are usually told that it is Offline and not available to print. This happens when we sent the print job from any of our devices...iPhone, Android phone, iPad, or Windows PC. We must then unplug and re-plug in the printer to wake it up to receive its print job. Even then it does not always work. This HP app does not acknowledge this situation or offer any solutions. Very frustrating.