It means you'll need to check your firewalls & your brand name & model of modem/router. The latter tend to have their own built-in NAT (or other) firewalls.

For computer softw firewalls see instrucitons here for the most common for configuring LW to have full access: http://www.limewire.com/english/content/firewalls.shtml

As for your modem/router it'd help if you could provide the above details of brand & model. Also force ip here: Force IP instructions & sample image (Use Port 6346!)