Problem for Aztech router configuration

Hi, I need help to configure my aztech router. my router model is Aztech NA8300 CABLE/DSL wireless super G. I follow the guide to configure the router.
The router is switch on 24 hrs. I have 2 pc connected to router. however, I face some difficulties to access internet.
Problems as below:
I have to reconnect the router manual at http://10.0.0.1/ oftenly.
or
One of the PC access to internet but the other PC cant access to internet until the router is reboot.

Is anyone can help me to solve above problem??? Thank you very much