That's a bad sign. It means something is blocking port 6346 which LW uses by default. If you set your firewall correctly then the other possibilities are your connection devices or your internet service provider (ISP). Yes isp's do sometimes use filters to against p2p sharing or decide to block ports that p2p sharing uses.

Without any info about your connection devices then I'm not sure what I can do. But if you said LW worked perfectly before & this is a sudden issue, then it looks like your isp might have done something. You could try another port. Go to LW's menu Tools>Options>Advanced>Firewalls & in the top section change the listening port to another. Try port 3500 or 22800 or 20282 or 80. Don't forget to press the apply button after changing each of these.