okay ,this is definitely another victim of anti-addicted system
either ur register ID number is random or your are under 18
but both symptom are same:
when you play more than 3 hours in the day .you will get half loot/exp or everything
when you play more than 5 hours ,you get none
in ur case , i think you have to make a call to netease customer service and in the meantime ,you need provide an True ID which is at least above 18