BB100+G300N ROUTER, 用咩WIFI手指接收較好?

買左隻TP LINK WN821N手指..
但經過SPEED TEST之後發現得4M
NOTEBOOK快好多..
係唔係隻USB接收太弱雞??
有冇邊隻比較好用?
唔該各位介紹一下~THX