If the driver has been installed successfully, maybe you can try to modify the Channel on the wireless router and see how it goes.

As far as I am concerned, with the WAN prefered mode, the Ethernet port is functioning as WAN port in order to use the network from the modem, once the modem is dead, the router will get the massage...

Maybe you can try to change the wireless channel on the router, and disable WMM to have a try.

How about changing the wireless channel on the router to a fixed number such as 1, 6 or 11?

As far as I am concerned, if you can get on line, the NTP sever will get an IP address by pressing Get GMT, if it won't, perhaps you can try a static NTP sever

Can you tell me how do you access internet when the computer is connected to the ADSL2 modem router? Is it like plug-and-play?