this is how I undertand it. Yes an ISP can block/restrict certain ports if they want. You would need to contact your ISP and ask if they are blocking the port you are using for LW. Tools options advanced, firewall configurtion, listen on port it should have 6346 entered. That is the port number you need to ask if they are blocking. I'm not sure about your particular ISP as I live in another Country. One of the experts here may be able to better answer your question, as this subject is a little beyond my knowledge other than what I have already said here.