Ulijin

Just in case anyone else googles their way here with similar issues. I figured out that I had set (or my kid clicking randomly did) my Ultimaker 2+ to 0.6mm nossle in Cura but with a 0.4mm nossle installed in the printer. Like the original poster I was getting a decent first layer but a badly under extruded 2nd layer etc. Probably other reasons why this happens to people, but something to check. Cheers.