Who is your ISP? Some ISPs have a fair access/fair useage policy & may throttle or even block p2p during their peak hours.

Try changing LW's listening port. Tools > options > advanced > super really advanced > firewall. Change LW's listening port to 65000 (or something in the range of 49152 - 65535) > ok. If you have port forwarding set up for a router then you'll need to add that same port number into the 'manual port forward' box > ok. And also change the port number forwarded within your router setup

If that doesn't help then please tell us your system details: System details - help us to help you -> Provide these details when you post!!!