u need to check on

- direction :  how u place your router ? vertical ? horizontal ? facing north, east south or west ?

- usb modem : what kind of usb modem are u using ? 3.6Mbps / 7.2Mbps / 14.4Mbps /21.6Mbps /28.8Mbps /43.2Mbps  ?

- temperature : your router is cool, warm or hot when u touch it after a long hour running

- firmware  : are u upgrade it to latest router firmware yet ?

- wireless or wired connection : using Lan cable connection confirm will be better than wireless connection

u need to turn your router in every direction and test to find out which direction works best for you,..

as for modem, higher power = better in performances 

log in 192.168.1.1 sign in with your id and pass to check what version firmware

example:

Latest firmware :  3.12.21 Build 120523 Rel.37880n

if ur firmware is not latest, just go to first pages first post and visit tp link malaysia websites to download the latest firmware