Running WEP and WPA2 in parallel is problematic, as most routers require you to choose one or the other

Next, configure the WEP router not to issue any IP addresses, but instead to forward DHCP requests to the master router. I'm not sure which of your routers is which, but the way you achieve this is the same in both: in the LAN settings page, under General Setup, select the button for "Disable Server", and in the box marked "DHC Server IP Address for Relay Agent", enter the address of the master router (normally 192.168.1.1). You might also need to enter this address in the Gateway IP Address box, and clear the entries for 1st IP Address and 2nd IP Address, so that the WEP router itself obtains an IP address from the master router.

Effectively, what you're doing here is turning your WEP router into an access point that simply acts as a bridge between your wireless devices and the master router. This will allow the master router to assign IP addresses to your WEP clients, after which it should be happy to handle internet traffic for them.

Source of Information :  PC Pro -April 2011