Q: Apple tv 2 cannot connect to library

Hi I  getting Cannot connect to  library message. I can access content(you tube etc) from main menu though so router must be ok? I have reset everything,rebooted everything,reinstalled Itunes and yosemite. I am running early 2009 imac on 10.10.1.  This is a recent problem but cant pinpoint toa specific event. I have had some issues with backups and other items for a while

Help!