Are you using the Huawei modem?
See that there is no clutter around it, as the reception might
be affected.
Sometimes signals at your block is poor. How is your mobile
phone connection?
Check see how the speed registers
http://www.speedtest.net/?s=367
Yup the stoopid Huawei thingy, but my phone line is singtel de.
Clutter there is none...