scottyzh,

 

I have no experience with Wanadoo or the Livebox router, but I can offer some suggestions.

 

First, while trying to get the various PCs to connect, configure the router with absolutely no security enabled, especially any kind of encryption.  Once you get connectivity, enable wireless security one step at a time.

 

Make sure all the equipment is running the most available drivers, especially the firmware in the router.  It looks like the Livebox router is an Inventel DV4210.  Maybe you can get updated firmware directly from Inventel.  I've seen your symptoms a number of times and in all cases upgrading firmware and drivers has solved the problem.  I would be cautious about this since Wanadoo may have proprietary firmware.

 

As a last option, get a more "mainstream" router from a brand name like Linksys, DLink, Belkin or Netgear.  Configure it for access point operation (as opposed to a router) and connect it to the Livebox via ethernet.  Disable the wireless capability in the Livebox.  I know this is a bit extreme, but at least you will have complete control over the wireless router instead of being at Wanadoo's mercy.