Alright, it sound as if you're on a network.

Ok, if you are the administrator or owner of the network, or can get access to one, this is what you can do.

Find the utility or program or interface used to access your hardware firewall or router. Go into that utility. There should be a setting, called something like "Firewall Passthrough" or "Firewall exceptions". What you're looking for is a way to open the port 6346. Because all your ports, or at least most of them, are closed, to prevent unauthorized traffic through them. What you need to do is tell the router that when it gets a message on port 6346, to "forward" or open the port to your computer. It's important that you "map" or tell the router to open 6346 and send the traffic (messages and files) to YOUR computer, or else it won't work if you send the 6346 traffic to someone else on the network.

I hope this helps.