Machine A:
  - Is running the HTTP server.
  - Is connected to the router, which is connected to the internet.
  - Has local IP 192.168.0.101. Is accessible through WAN at IP 66.46.168.204 (Which is the router's IP, I assume)
From there:
  http://localhost:80/  -> Will reach the HTTP server.
  http://66.46.168.204:80/ -> Will not reach the server.

Machine B:
  - Is connected to the internet, and is not running anything in particular.
From there:
  http://66.46.168.204:80/ -> Will reach the server.