What Is The Best Blue Ray Upconvert I Heard That Blue Ray Players DONT PLAY Older Dvd's .. Is That True ?

I heard that blue ray players DONT PLAY older dvd's .. Is that true ? - what is the best blue ray upconvert

U should you play a HDMI upscaling DVD player old DVDs and Blue Ray .. I want a player B / R and wanted to know if they play the largest