Try with the Port:
Server Adress: PublicIP:9987
Port Forwarding should be something like this:
External UDP 9987 to Internal (IP of your PC e.g. 192.168.xxx.xxx) and Port 9987
In addition you have to allow TS Server communication in you Firewall.
Try with the Port:
Server Adress: PublicIP:9987
Port Forwarding should be something like this:
External UDP 9987 to Internal (IP of your PC e.g. 192.168.xxx.xxx) and Port 9987
In addition you have to allow TS Server communication in you Firewall.