Sorry I forgot to reply to you earlier.
This is what you should see when you go to that test site url: Test site example image.
If you are not able to reach that page with your browser, it suggests 'something' is blocking the default LW connection port (& maybe the program itself.)

I can tell you the Linksys router model you have is a reknown problematic model. Linksys never fully fixed the firmware problems it has. ie: is unreliable when busy, and UPnP often does not work. Port forwarding the device improves reliability. I cannot say for sure that the linksys device is what's blocking you connecting to that page however. Your ISP, Orange 'might' be at fault.

In your OSX preferences -> Security -> Firewall, you are sure this is disabled?