SimpleSYN uses the Microsoft® Peer Name Resolution-Protocol (http://msdn.microsoft.com/en-us/library/bb726971(en-us).aspx) to find the SimpleSYN server over your local network or the Internet. The Peer Name Resolution-Protocol uses IPv6 for communication.

Under Windows XP the firewall settings for the Peer Name Resolution-Protocol are not automatically set by SimpleSYN. You have to set up the Windows Firewall manually. You can find the firewall settings for the Peer Name Resolution-Protocol here.