The Problem: You want
to run an application that requires a specific port on your network to
be open. You follow the directions that the app developers provide only
to get the error, "Port closed."
Quick Fix: Usually, this isn't a problem with a user's
configuration. It's a problem on the Internet service provider's side.
ISPs will often block ports to strengthen your network against hackers
and intruders. Before frantically going through your configuration
steps again, check to make sure the port you are setting up for
forwarding is not blocked by your ISP. Use a tool like the Open Port Check Tool to see if the port you need opened is being blocked. If so, contact your ISP.
Internet Connection Tips; Port Forwarding Does Not Work