The problem might be with your modem/router because many have internal NAT firewalls. So the usual answer is to either enable UPnP on the device or forward a port. But you'd need to telnet into the device to do this.

Oh I see you're connected at an office LAN. That's more complicated. The office probably have their own hardware firewall. No simple answer there. See if the tech administrator will open port 6346 for you on the LAN connection device. ie: open both TCP & UDP for port 6346.

As far as software firewall goes, one at least should be turned on. But don't run XP firewall & Norton firewall together. They would clash & give you less security, not more. And LW would also have a problem with it. So configure norton: Configuring Norton Internet Security