thanks bro for great post. just now tm staff change my router from dlink wbr2300 to rgx4400 due my dlink lan4 port faulty.
didnt know this router much better than dlink wbr2300.
anyway just talking with the staff, why they didnt change to dlink 850L, he said that router not good performance of the wifi. and he said this rgx4400 much better