255.255.255.255 is enough for a broadcast IP address, it covers anything. Sidenote, even Borgchat supports binding to 0.0.0.0 😀. Sygate usually shows a prompt asking whether or not to allow the program to access the net (or LAN). Make sure it has allowed access. If you're not sure, check the logs and see if it is blocking traffic on port 7550 or whatever you have changed it to.