Hmm, maybe some ports are mixed up in Firewall. What Operating System do you use? I guess everything is working normally over the net, except LW? Well, those are problem lot of ppl have and there is always solution for it. You are not the only one
You have same connection like I do so I don't see any reason why LW can't detect Internet connection... You have to make sure that those antivirus programs do not block LW. And Firewall also. There is offcourse exception option in every of this programs. They just don't let LW ports to go to internet. Try shutting them down (antivirus programs and firewall) and see if LW works.
Let us know and good luck.