Blocked incoming generally means a firewall. It could be due to a softw firewall or a hardware device such as modem/router, etc. The way the network & connection is set up probably.

I'm not sure from here. Might have to pass you to Stief to deal with. He might have some ideas.

Just one last thought, temporarily change your port for listening to port 80. LW Prefs>Advanced>Firewalls. (Don't forget to press Apply.) And repeat the above experiment.

My only other thought is to use a proxy.