i have problem with w9960 i bought last tuesday

is that i find sometime in my cable connected pc speed sometime >>>exceed total down stream bandwidth i made

up to normal line speed while all wireless funcioning normally under bandwidth rules while this computer is not sometime not all the time!!!!!!!

after i restart router it return to functioning under bandwidth

how can i fix this ??

router working properly in all aspected except for this pc sometime !!!!

any help appreciated 

thank you 

happy to join you